Band 44, Heft s1

This work is focused to carry out the investigation of wavelength division multiplexing (WDM) approach on free space optical (FSO) transmission systems using Erbium Ytterbium Doped Waveguide Amplifier (EYDWA) integrated as post-or pre-amplifier for extending the reach to 30 Km for the cost-effective implementation of FSO system considering weather conditions. Furthermore, the performance of proposed FSO-wavelength division multiplexing (WDM) system is also evaluated on the effect of varying the FSO range and results are reported in terms of Q factor, BER, and eye diagrams. It has been found that, under clear rain the post-amplification was performed and was able to reach transmission distance over 27 Km, whereas, the FSO distance has been limited at 19.5 Km by using pre-amplification.

The doping effect on the reservoir carrier temperature of the electron and hole in quantum dot optical amplifiers (QD SOAs) has been formalized and modeling, taking into account the most of carrier heating (CH) contributions such as; free carrier absorption, carrier heating time relaxation, interdot relaxation time, occupation probability of dot level, injected current and electron-hole interaction. The theoretical simulation shows the carrier temperature increasing straight forward with increasing the surface density of the donor and accepter which had not studied earlier as the best of our knowledge. It clears that, the surface carrier concentration of donor or acceptor atoms supplying more hot carriers for wetting layer (WL) which is leading an increasing the carrier temperature. In other word, the long life time of carriers from WL to Quantum Dot (QD) states is very high. Consequently, the collision of carriers and nonradiative relaxation are increasing the CH effect. Also, the majority of carrier is responsible on the increasing of electron or hole temperature, so the variation electron temperature in N-type is higher than hole in valence band, while the reverse is done with doping with P-type.

The demand for larger bandwidth to carry high capacity data in optical networks is increasing. Thus, it is expected to replace all digital logic with optical logic soon. Privacy and data security are also of utmost importance in all-optical networks. Generally, all-optical encryption has been carried out using (i) highly nonlinear fiber (HNLF) and (ii) Semiconductor Optical Amplifier (SOA) with interferometric structures. However, the former is limited by the requirement of a lengthy fiber and the latter one with more number of nonlinear components. In this work, an all-optical encryption process using nonlinear effects and four-wave mixing (FWM) in SOA without interferometric structure is presented for different number systems. The basic idea of the proposed system is to use delay operations which are carried out by duo binary modulation units whereas the encryption using single SOA is possible by FWM nonlinear effect. This combination of novel design for different number systems is optimized through SOA structural parameters, pump and probe signal power, and wavelength. Through optimization, the performance improvement is assured by a good extinction ratio of 11.5 dB for the active region length of less than 200 µm. Compared to the existing techniques, the quality factor is 2.28 times and 1.52 times better than HNLF and SOA-MZI, respectively.

This work studies the total gain of the InTlAsSb quantum dot structure, which is not studied earlier. Adding thallium to structures makes it emit at larger wavelengths. The nonlinear effect of the injected signal power is examined for three quaternary thallium structures: In 0.85 Tl 0.15 AsSb, In 0.93 Tl 0.07 AsSb and In 0.97 Tl 0.03 AsSb. The gain peak was increased by four times and the wavelength was shifted to longer one for the In 0.97 Tl 0.03 AsSb quantum dot (QD) structure. This quaternary QD structure extends the emission wavelength to more than 12 μm which is important in long-wavelength infrared applications. The nonlinear behavior of these QD structures is also addressed. It is shown that the structure In 0.97 Tl 0.03 AsSb has a deeper spectral hole burning which is adequate for nonlinear signal processing applications.

We have introduced the comprehensive optical-to-noise ratio (OSNR) to investigate simultaneously the effects of all three major linear noise sources in distributed Raman fiber amplifier (DRFA). The total noise power contains double Rayleigh backscattering (DRB) noise, amplified spontaneous emission (ASE) noise, and relative intensity noise (RIN). Also, we have introduced an approximated gain profile approach, which helps in evaluating the OSNR for higher-order pumping (HOP) configuration for backward, forward, and bidirectional DRFA schemes. Finally, by applying the dynamic and static full-numerical computations on a system of eight wavelength division multiplexing (WDM) channels (for amplifier lengths of 70, 140, and 210 km), we demonstrated that for RIN frequencies greater than 100 kHz, the higher-order bidirectional pumping scheme exceeds the backward schemes by 12 dB.

In this paper, design of erbium-doped fiber amplifiers (EDFA) based 16 channel wavelength-division multiplexing (WDM) system for different pump powers and input signal levels using counter propagating pumping scheme is reported. Wavelength range between 1548 and 1560 nm in C-band with channel spacing of 0.75 nm at a bit rate of 10 Gbps are used. Input power given to all the channels is taken between −20 and −35 dBm with 3 dBm variation. Pump power levels between 100 and 500 mW at 980 nm wavelength are used. Low gain flatness with high gains and low noise figures are achieved with the proposed scheme.

Semiconductor optical amplifier-based polarization rotation is utilized in designing all-optical AND gate at 100 Gbps. The AND gate shows high extinction ratio (ER ∼ 15 dB), contrast ratio (CR ∼ 18 dB) and quality factor (Q-factor ∼ 16 dB). The effect of the amplified spontaneous emission noise on the performances is also investigated. The AND gate has relative eye opening (REO) varying from 93.52 to 97.1% for 10–30 dB unsaturated gain. Using the AND gate a majority voting gate is designed and analyzed and has Q ∼ 11.7 dB with REO ∼ 91%.

In this paper, the performance of single and double-pass thulium-doped fiber amplifiers (SD-TDFA and DP-TDFA) is analyzed in the short wavelength (S-band) region. The effect of thulium-doped fiber (TDF) length, input signal power, and input pumping power on the amplifier’s performance is comprehensively investigated on basis of gain and noise figure (NF). DP-TDFA showed a higher gain compared to single-pass configuration and that is due to double-propagation of the forwarded and amplified spontaneous emission (ASE) signal into the TDF which maximizes the achievable gain in the S-band region. At a gain medium length of 8 m, the proposed DP-TDFA showed higher gain enhancement over SP-TDFA at an input power of −20 dB compared to −40 and 0 dB input signal powers. The gain enhancement at 1470 nm is 5.6 dB, while the maximum recorded gain with the proposed double-pass configuration is 14.7 dB.

Optical communication gained popularity in past few years. Optical communication has many distinct advantages over copper cable based electronic communication. Optical switches are integral part of optical networks which are used for rerouting of packets and also plays important role in contention resolution of the packets. These switch uses fiber delay lines (FDLs) act as optical memory. In past analysis of the switch is done by considering loss, power and noise and finally bit error rate (BER); however dispersion was neglected which is an important parameter in high speed communication. In this paper, design analysis is done by considering dispersion compensation along with optical amplifier noise.

Present communication deals with the design and analysis of all-optical NOR and NAND gates using Quantum dot Semiconductor Optical Amplifiers (QDSOA). The design uses no interferometer structure but cross gain modulation is utilized for operation. The structures are simple and simulations at a rate of 1 Tb/s are processed. For unsaturated gain 30 dB, the logic gates show high values of ER (29.82 dB, 16.93 dB), CR (29.6 dB, 21.33 dB), and Q (25.4 dB, 13.2 dB). This ensures practical feasibility and high quality of the proposed gates.

This paper focuses on designing of a 10 Gbit/s-10GHz hybrid Orthogonal frequency division multiplexing (FDM) based Radio over Free Space Optics (Ro-FSO) transmission link using optical single sideband modulation format and its performance has been compared using a different number of transmission beams. The proposed link has been simulated and compared using 1-beam, 2-beam, and 4-beam in the system. We show that by using the 4-beam system in the OFDM-Ro-FSO link, a 3000 m range has been achieved reliably, which a notable improvement when compared to previous work is. Also, we show an improved performance of the system by using an enhanced detection mechanism using a Square root module (SRm) at the receiver side.

In this paper, a hybrid-subcarrier-intensity-modulation (hybrid-SIM) technique for the performance improvement of free-space-optical (FSO) communication system has been proposed. Subsequently, for further error performance improvement, avalanche photodiode (APD) based receiver is used in the proposed system. The system performance is analyzed at various atmospheric turbulence levels over weak and strong turbulence channels. The bit error rate (BER) is theoretically derived using Gauss–Hermite approximation and Meijer-G function and it is simulated in the MATLAB environment. The simulation result shows that the BER performance of hybrid-SIM is better than BPSK-SIM technique irrespective of the channel types and also the significant BER performance improvement is observed by APD receiver.

The development of communication technology requires a new type of passive optical network (PON) architecture. The architecture needs to be based on time division multiplexing (TDM) of 40 Gbit/s downstream and 10 Gbit/s upstream, and it can realize TDM PON prototype. The PON system achieved the system distance of 120 km supporting 128 ONU with power budget of 53.5 dB via polarization multiplexing differential quadrature phase shift keying format signal which employs the coherent receiver and the digital signal processing.

In this paper, we develop a novel demultiplexer design for Coarse Wavelength Division Multiplexer (CWDM). The device consists of multi-layer inhomogeneous semi-conductor material, where the refractive index of each layer is graded according to a predefined profile. The proposed design exploits the ray’s spatial shift that results from the material dispersion as different wavelengths propagate through the different layers of the device. Our design forces the multiplexed light to refract after propagation for short distance within the device leading to smaller device size while providing the needed spatial shift between the ray’s of the adjacent multiplexed wavelengths. The proposed structure can be easily implemented using the well-established technology utilized in fabricating existing graded-index fibers. The impacts of the various design parameters (such as the incident angle, number of layers, the layer thickness, the spacing between adjacent wavelengths, the refractive index difference) on the amount of achieved spatial shift between the adjacent wavelengths and the size of the device are investigated. Compared to previous proposed techniques, our device can be easily fabricated to provide higher spatial shift while reducing the device size with by controlling the different design parameters.

Photonic crystal waveguides provide a way to manipulate the performance of an optical signal in an ultra-small volume and are quite viable in designing chip-based components that will work all-optically. Here, in this article an all-optical half adder is proposed. It is based on a square lattice photonic crystal waveguide in which silicon rods are arranged periodically. The photonic crystal offers a wide photonic band-gap in the desired region of telecommunication wavelength (i. e. near λ = 1550 nm. The performance of half Adder is measured using the contrast ratio and response time. The contrast ratio for sum and carry is 5.2 dB and 16.7 dB, respectively. The proposed half adder is miniaturized in size and having a footprint of 49 µm 2 only. The total response time of the proposed adder is 1.4 picoseconds only. So, the device offers a high bit rate of 0.714 Tb/sec. The proposed half adder is an optimum choice for its application in on-chip optical integrated circuits.

This study outlines the distributed feedback laser for signal power amplitude level improvement in the long spectral band of 1550 nm wavelength within supporting pumped wavelength of 1480 nm. The bias and modulation peak currents based distributed feedback laser are varied in order to test the signal power level, peak signal amplitude variations after the fiber-optic channel and light detectors. The signal power level, peak signal amplitude is measured against spectral wavelength and time bit period variations. The study emphasis the signal power level, peak signal amplitude are enhanced for the best selection values of both a bias current at 45 mA and modulation peak current at 0.5 mA.

In this paper, we report the performance of a carrier depletion Silicon PIN phase shifter with over layer of 130 nm. It is observed that an optimum intrinsic gap of 250 nm for a device length of 5 mm at 2 V, resulted in Extinction Ratio (ER) of 23.41 dB and Bit Error Rate (BER) of 1.00 × 10 −7 is obtained for 50 Gbps. The phase shifter is also designed for length 2 mm with an intrinsic gap of 100 nm at an operating voltage <4 V. The study also reveals that the proposed design for Mach-Zehnder modulator operating at a data rate of 100 Gbps for the concentration of P  = 7 × 10 17  cm −3 and N  = 5 × 10 17 cm −3 gives better BER and phase performance. The proposed design was also analysed in an intra-data centre communication setup of fibre length 15 km.

In this paper, 4 × 2 encoder is proposed by combining optical waveguides and the ring resonators. The proposed structure has four input ports, two control input and two output ports. The hexagonal photonic crystal structure has the square lattice of chalcogenide glass rods with the refractive index of 2.1 in air. Maximum bit rate of 10 Tb/s and response time of 0.1 ps is obtained using the proposed cross-layered arrangement of the chalcogenide glass rods with circular inner arrangement. The size of the proposed structure is 18.6 µm x 24.6 µm. Moreover, the contrast ratio of outputs is found to be 28.3 and 48.45 dB. The fundamental structure for the proposed encoder is also designed and analysed for validating the desired bandgap at the resonant wavelength of 1550 nm.

A 1 × 2 plasmonic demultiplexer with a rectangular metal-insulator-metal (MIM) waveguide comprising one input port and two output ports has been proposed. The proposed demultiplexer is based on the principle of interference of surface plasmon polariton waves. By placing the output port at the designed position along the rectangular MIM waveguide, the desired wavelength can be extracted from the mixture of the wavelengths. Results were simulated using finite element method (FEM) technique and plot of field and its intensity were obtained for both the wavelengths. The results agree with the proposed theory. Power transmission of more than 80% at the desired port with a suppression of more than 90% at the undesired port is obtained for both the wavelengths. A low crosstalk of less than −11.06 dB with a low insertion loss of less than 14.32 dB are measured. It is shown that the wavelength selectivity of the plasmonic demultiplexer is further dependent on the width of the MIM waveguide as well as the materials chosen. The design can be further extended to a 1×N demultiplexer by appropriate selection of position of the output ports.

Recently, the photonic crystal–based optical components and devices have attracted many researchers’ attention because of its nanoscale size which makes it suitable for the photonic integrated applications. Hence, the design of all-optical switch based on photonic crystal structure have been investigated in the past few decades to meet the requirement of ultracompact size with optimized performances such as fast response time, high extinction ratio with low insertion loss. Here, the design of directional coupler–based all-optical switch operating at the wavelength of 1550 nm is proposed with new design values. The resonant operating wavelength of the switch is identified with the help of finite element method. Then, the cross-state switching operation is analysed with the help of finite-difference time-domain method by applying a nonlinear optical Kerr effect switching mechanism. The important performance metrics of the proposed design such as insertion loss, extinction ratio, directivity and the response time are obtained as −0.008 , 26.98, 20.44 dB and 0.13 ps , respectively. The total footprint of the proposed optical switch is approximately 128 µm 2 .

In this paper, we propose an all-optical integrated 2-to-4 decoder and a 1-to-4 demultiplexer circuit using SOA based MZI (Mach–Zehnder Interferometer) architecture. The proposed device has been applied an enable signal along with two data input signals at the same wavelength. Four output signals from 2-to-4 decoder and 1-to-4 demultiplexer have been attained at the same wavelength. The output timing diagrams of 2-to-4 decoder and 1-to-4 demultiplexer for different input data conditions with clear eye opening patterns confirms the operation of the proposed logic device at 10 Gb/s. Maximum value of extinction ratio, contrast ratio and minimum value of amplitude modulation achieved for the different output waveforms are 12, 9.5 and 0.1 dB respectively. Easy integration with active and passive devices and simple architecture makes this device suitable for all-optical processing.

In this paper, ultra-fast, compact and high contrast ratio all optical half subtractor based on photonic crystal designed and simulated. The proposed design will be constructed using both threshold switching and interference of beams mechanisms. The proposed structure is composed of six waveguides and a nonlinear ring resonator. The simulation results show that the contrast ratio for D and B ports were obtained about 18.80 and 15.05 dB, respectively. Also the maximum rise, fall and steady-state times and total footprint for suggested all optical half subtractor are 0.5, 0.25, 1.5 ps and 234  μ m 2 , respectively.

Using binary phase shift keying is one of the popular methods used for designing optical logic gates. In this paper, we used optical waveguides with different lengths for designing an all-optical XOR gate. The proposed structure works based on constructive and destructive interference of optical beams. The time delay of the proposed structure is 0.5 ps.

We have simulated four bits data sequence generators based ytterbium-doped fiber amplifiers for upgrading max. Q factor and min. BER. Optical power variations against time duration after fiber cable length of 250 km with the bits sequence generators of 0101, 1000, and 1010 respectively are simulated. As well as the electrical power/total received power variations against frequency after photodetector receiver with the bits sequence generators of 0101, 1000, and 1010 respectively are discussed in details. Moreover, the signal power amplitude level with the time period duration after photodetector receiver/3R regenerator with the bits sequence generators of 0101, 1000, and 1010 respectively are clarified to show the max. Q factor and min. BER values for each case.

In this work, photonic crystal (PhC) based all-optical 1 × 2 demultiplexer is designed for optical computing and optical signal processing. The structure is implemented with two-dimensional PhCs using T-shaped waveguides with an optimized silicon rod radius of 0.2a. Performance of the proposed structure is verified and analyzed by using the finite-difference time-domain method. The design of all-optical demultiplexer is operated based on optical interference effect at a wavelength of 1550 nm. Proposed design occupies less area of 8.4 × 5.4 µm, provides a contrast ratio of 18.53 dB, 94.52% of minimum and 100% of maximum transmission ratio and it has less insertion loss of 0.017 dB; therefore, the proposed device is suitable for photonic integrated devices.

In the present scenario, data centers serve many functionalities like storage, transfer of data, supporting web applications, etc. In data centers, various levels of hierarchy different types of switches are required; therefore, multifunctional data centers are desired. This paper discusses a novel design for optical switch which can be placed at various levels of hierarchy. In the proposed design, multifunctionality contention resolution schemes which consider electronic and optical buffering and all-optical negative acknowledgment (AO-NACK) are considered. In buffering technologies, contending packets are stored in either in electronic RAM or in fiber delay lines. In case of the AO-NACK scheme, contending packets are blocked, and a negative acknowledgment is sent back to the transmitting node and blocked packets are retransmitted. For various considered schemes, Monte Carlo simulation have been performed, results in terms of packet loss probability are presented, and it has been found that the performance of optical buffering is much superior to electronic buffering and AO-NACK schemes. It is found that, in the AO-NACK scheme, the numbers of retransmitted packets due to contention blocking are 33,304 which can be reduced to 7, by using a small amount of buffer at each node.

Optical decoders are required for optical routing. In this paper we presented the design procedure and simulation results for 3-to-8 optical decoder, which was designed using nonlinear ring resonators inside two dimensional photonic crystals. The proposed structure was simulated using finite difference time domain method. Based on the simulation results the maximum delay time of the structure is about 2 ps. Also the worst transmission values for logic 0 and 1 are 10% and 78%, respectively.

In this work, we propose a slab waveguide structure based on a magneto-photonic crystal, formed by a triangular lattice of circular air holes in a cerium-substituted yttrium iron garnet (Ce-YIG) medium grown on a silica (SiO 2 ) substrate; in this structure, we have studied the width of the photonic band gap (PBG) using the expansion plane waves method in three dimensions to reach and optimize the complete PBG, centered at the telecommunication wavelength, also a theoretical study of the conversion mode, reported and studied the effect of some parameters such as the radius and the thickness using a beam propagation method in two dimensions. In our proposed structure, the maximum conversion modes ratio equal to 98% with a low coupling length LC = 15 µm is obtained for gyrotropy g  = 0.36 and Faraday rotation FR = 1500 × 104 deg/cm.

Nowadays to process information on high speed and to reduce the complexity of digital devices, optical digital computational techniques are required. Many complex signal processing functions such as multiplexing, optical switching, addressing, coding/decoding are implemented using optical digital computational techniques. Optical logic gates are one of the most essential computational elements to design combinational and sequential circuits in optical signal processing. In this paper, all optical logic gates are designed with optimized structure of 2 × 2 Mach–Zehnder interferometer optical switch using Ti:LiNbO 3 based waveguide at 1.46 µm employing electro-optic effect. Different design structures to realize all-optical logic gates are presented and compared with the previously designed optical logic gates. The mathematical description of all optical logic gates using cascaded structure of Mach–Zehnder interferometer switch is also defined. The performance parameters of designed optical logic gates have been analyzed by beam propagation method and the obtained results are verified by MATLAB.

A chirped long-period grating inscribed in a planer optical waveguide sensor is demonstrated. The distribution of electric field within the structure has been obtained using boundary condition for the electric field equations at different dielectric boundaries. The transmission spectrum of the proposed sensor is obtained by transfer-matrix method. Further, the sensitivity for ambient refractive index and temperature has been analysed by observing the shift in resonance wavelengths. The presence of two dips in the transmission spectrum effectively doubles the sensitivity in comparison to the single resonance structure. We have achieved refractive index sensitivity of 5600 nm/RIU and temperature sensitivity of 0.8 nm/ °C, respectively.

In the paper, one input optical gates i.e., INVERTER and BUFFER have been designed using some basic assumption to analyze with the help of Semi-conductor Optical Amplifier based Mach–Zehnder Interferometer structure. The results are optimized by iterative process. The proposed design of optical gates presents low complexity, high scalability and more feasible to evaluate through digital Boolean analyzation. The digital Boolean analyzation is analyzed by some basic Boolean rules and assumptions which makes the design more digital so that it can be compatible for more than one input optical gates also. Optical Gate is designed to get constructive and destructive interference for pump and probe as they are injected into SOA simultaneously. The phase modulation is converted into intensity modulation which gives a Boolean result. The paper is optimized by Eye diagram, Q factor, wavelength spectrum and frequency chirp for both the gates. The comparative results of extinction ratio for both the gates have also been discussed. The design is supported by theoretical analysis, simulation tool (Optsim) and Boolean explanation. The proposed designs are constructed with same pattern which supports the same Boolean analysis.

The multiplexer is a combinational circuit that transfers multiple data inputs over a single output line. The input data are selected and transferred to the output line based on the selection line. In this work, 2 × 1 and 4 × 1 multiplexer is proposed. The proposed multiplexer has been worked out using the electro-optic principle. It is implemented using lithium niobate-based Mach–Zehnder interferometer (LN-MZI). LN-MZI is used as an optical switching device. The performance parameters extinction ratio, contrast ratio and insertion loss have been computed and found 31.31, 28.02 and 0.043 dB respectively.

Free-space optical (FSO) communication is a wireless optical data transmission technology with a high data transmission rate. It has received much attention in recent years as it is cost-effective and has license free operation. It is line of sight free-space communication technique where optical signal severely degraded from atmospheric losses especially due to weather conditions; hence it restricts the link range and data carrying capacity. Therefore, a 16-channel ultra-dense wavelength division multiplexing–free space optics (UWDM–FSO) system each having each 10 Gb/s data rate is proposed to enhance the capacity and performance of FSO system. To authenticate the performance of the proposed system, investigation for different modulation formats such as nonreturn to zero (NRZ), return to zero (RZ), carrier suppressed return to zero (CSRZ) and duo binary (DB) are reported. Further, to reduce the atmospheric interference, multiple input multiple output (MIMO) technique is integrated into the proposed system. The outcomes of MIMO–UWDM–FSO link revealed a significant improvement in the bit error rate (BER), eye diagram and Q-factor, under different weather conditions. It is also observed that NRZ modulation formats perform better than RZ, CSRZ and DB formats.

In this paper, we are going to propose a novel structure of all-optical NOT, XOR and XNOR logic gates are presented using a two-dimensional photonic crystal (2D-PhC). This structure is optimized by varying the radius of the cavity, to obtain a quality factor Q  = 1192, and also has several ports of entry and one port of output. The size of each structure is equal to 85.8 μm 2 . The contrast ratios for the structures proposed all-optical NOT, XOR and XNOR logic gates between levels “0” and “1” are, respectively, 25.08, 25.03, and 14.47 dB. The response time for the three logical gates is 8.33 ps, and the bit rate is calculated at about 0.12 Tbit/s, all simulations are based on both numerical methods such as finite difference time domain (FDTD) and plane wave expansion (PWE). Designed logic gates are characterized by low power consumption, compactness and easy integration.

All optical logic gates are building blocks for all optical data processors. One way of designing optical logic gates is using threshold switching which can be realized by combining an optical resonator with nonlinear Kerr effect. In this paper we showed that a novel structure consisting of nonlinear photonic crystal ring resonator which can be used for realizing optical NAND/NOR and majority gates. The delay time of the proposed NAND/NOR and majority gates are 2.5 ps and 1.5 ps respectively. Finite difference time domain and plane wave expansion methods were used for simulating the proposed optical logic gates. The total footprint of the proposed structure is about 988 μm 2 .

In the current era of data communication everyone deals with the huge amount of data in form of text, audio, video and different other formats in which everyone want a secure and higher bandwidth channel to transmit and receive so, only the optical channel provides the solution of above said problem. The only difficulty with the existing model that the data from electrical domain first converted in form of light (optical domain) at the transmission end while after receiving the data at the receiver end it will be further converted in form of electrical signal for extracting the message. This type of conversion from one domain to other gives the energy loss. In the current research article, we proposed a model of optical processor which transmit and receive the data without conversion which provides an energy efficient optical technology. By adding reversibility, heat bender can be further reduced. In this manuscript, an arithmetical logic unit has been created, a photonic reversible complete subtractor and an irregular logic portal. SOA-MZI structure is the basic component of the architecture. The method is mainly carried out by the semiconductor Amplifier, using nonlinear properties such as cross-gain modulation and cross-phase modulation. The efficiency deciding factor for the whole system is 21.23 and 53.27 dB in the average extinction ratio. The cost of the arithmetic logic unit optically constructed is 9.

Having uniform channel spacing is very important for all optical communication networks. In spite of its importance designing optical de-multiplexer with uniform channel spacing seems to be very complicated. In this paper we proposed an all optical de-multiplexer with uniform channels spacing. Four high quality factor ring resonator were used for designing the desired structure. In the proposed structure the output channels are at 1555.2, 1556.2, 1557.2 and 1558.2 nm. The channel spacing for all of the adjacent channels are 1 nm. Also for the final structure the quality factor values vary from 7758 to 15,582.

Increasing the speed of operation in all optical signal processing is very important. For reaching this goal one needs high speed optical devices. Optical half adders are one of the important building blocks required in optical processing. In this paper an optical half adder was proposed by combining nonlinear photonic crystal ring resonators with optical waveguides. Finite difference time domain method wase used for simulating the final structure. The simulation results confirmed that the rise time for the proposed structure is about 1 ps.

The communication network based on the optical system requires more precise and efficient devices and equipment. Optical ring resonator is a versatile device used as a filter, delay line, add/drop multiplexer, switch, sensor and analyzer etc. We modelled the new symmetrical quadrature optical ring resonator (SQORR) and proposed four different topologies architecture for the multiple optical ring resonator. The performance of the proposed symmetrical quadrature optical ring resonator is assessed using regression based machine learning (ML) approach utilizing an Artificial neural network (ANN) with various checks are done to validate the approximations like error histogram, time series response, error autocorrelation, input-error correlation and mean-square-error (MSE). The best validation performance is 8.8486e-9 stopped at 103 for rhombus topology, 8.347e-9 stopped at 242 epochs, 8.8486e-9 stopped at 311 epochs for horizontal topology and 5.8012e-09 stopped at 373 epochs for square topology. The significance of the work is to increase FSR (free spectral range) by adding rings and wide FSR achieved 299.79 THz (maximum) and throughput of 0.027 W/m for rhombus topology and other performance parameters of the optical ring resonator using symmetrical rings. Such structure is small in the size and easy to fabricate. Even by the same number of rings using different topologies structure, we can vary the performance parameters as per the different applications.

We report here the first theoretical prediction of coupling efficiency of the laser diode to single-mode graded-index fiber coupling via cylindrical microlens on the tip of the fiber in presence of possible transverse and angular mismatches. Moderately efficient cylindrical microlens on the fiber is easily fabricable and graded-index fiber has less sensitivity to macro as well as micro bending. Thus this coupling device emerges as a potential candidate in the field of coupling optics. The analysis takes into consideration the allowable aperture provided by cylindrical microlens. Further, we shall consider here the coupling in the vertical plane only since the coupling in the horizontal plane has poor performance. Using the relevant ABCD matrix of refraction for a cylindrical lens in the vertical plane, we prescribe analytical expressions of the coupling efficiencies in presence of said kinds of misalignments. In our analysis, we use Gaussian field distribution for both the laser and fiber fields. We carry on our investigation for two commonly used wavelengths namely 1.3 and 1.5 µm. As an example of graded-index fiber, we use some typical step, parabolic, and triangular index fibers in our study. The execution of the prescribed formulations involves little computation. Thus the evaluation of the concerned coupling efficiencies is very much user friendly. The present analysis surfaces the tolerance factors of the coupling devices. Accordingly, the results will prove beneficial to designers and packagers in respect of the design of such coupler involving cylindrical microlens in the field of optimum launch optics.

Optical packet switching has gained lot of popularity in last a few years due to its advantages like, large speed, more bandwidth and very less crosstalk. But due to immature optical fabrication and designing technology OPS is still beyond reality. However, many of the optical components are commercialized and some of them are still in laboratory. Thus, for optical switches which are considered as future generation routers, many switch architectures are proposed by using different sets of optical components. This paper presents a detailed review of notable switch designs in past 20 years, and also presents a comprehensive literature survey of the notable papers related to optical packet switch designs.

Wavelength division multiplexed passive optical is promising technique to achieve a high data rate and large number of user. The notable advantages of WDM PON is the combination of reliability, cheap in cost, accessible bandwidth, high security, large optical reach and it can support large number of ONU. There are multiple approaches to achieve high-speed WDN PON using different transmission techniques. In WDM, multiple lasers are required which increase the cost of the system. To reduce cost, an optical multicarrier generation system is proposed. An economical multiple carrier generation with the incorporation of sine generator and Mach–Zehndar modulator is demonstrated. Utmost work of sine generator and dual drive modulator was to attain low cost functioning of passive optical networks. Multicarrier generation was done and replacement of laser carriers with optical multicarrier generator. Carriers were generated with the frequency spacing of 20 GHz and these carriers were used in the passive optical networks with the tone-to-noise ratio of 40 dB, amplitude difference of 1.4 dB. For the transmission of downstream in the PON, differential phase shift keying was employed at 10 Gbps data speed. Transmission distance achieved was 30 km using single-mode fiber and this was a part of optical distribution network. Optical network unit was next part after ODN and signals were received with balanced receiver. Moreover, half signal was given to intensity modulator for the signal re-modulation. Bit error rate of 10 –9 was achieved at all channels in the downstream. An upstream of 10 Gbps was accomplished in the passive optical network.

In this paper a simple and novel scheme to develop optical logic gates for fast switching. This can be obtained by sending two laser beams coaxially through nonlinear media with saturating nonlinearity. The nonlinearity in the optical properties on the medium is assumed to be cubic quintic nonlinearity. Semianalytical solutions of the wave equations for the fields of incident laser beams have been obtained by using a variational formalism. Emphasis are put on dynamical variations of beam widths of the laser beams with distance of propagation through the medium. It has been found that the weak beam modulates the intensity variations of the strong beam that giving rise to the possibility of an optical transistor. Combinations of these optical transistors can further be used to obtain logic gates.

In this study, we are going to design all optical 1-bit comparator by combining wave interference and threshold switching methods. The final structure composed of two nonlinear ring resonators and seven waveguides. The functionality of the suggested logical structure is analyzed and simulated by using plane wave expansion (PWE) and finite difference time domain (FDTD) methods. According to results, the proposed all optical 1-bit comparator has faster response and smaller footprint than all previous works. The maximum ON-OFF contrast ratio, delay time and area of the suggested optical comparator are about 16.67 dB, 1.8 ps, and 513 µm 2 , respectively.

In this paper a high speed optical half adder is designed. The working mechanism of the proposed structure is based on optical threshold switching. Three nonlinear ring resonators are used for this purpose. These nonlinear ring resonators are created by adding doped glass based rods inside the resonant rings. The proposed structure works with optical waves with central wavelength and optical intensity equal to 1550 nm and 1 W/μm 2 respectively. The rise time is 2 ps.

Optical logic gates can play crucial roles for designing all optical data processing circuits. Photonic crystals are one of the suitable platforms that can be used for designing all optical devices. In this paper an optical XOR gate was designed using nonlinear ring resonators. The proposed structure works are based on threshold switching. The working wavelength and the switching threshold of the resonators are 1550 nm and 1.8 W/μm 2 , respectively. The rise time is about 1 ps and the ON/OFF contrast ratio is about 16 dB.

In the present work, the performance of the all-optical AND logic gate using four wave mixing in wide band semiconductor optical amplifier (SOA) has been analyzed for different modulation formats. The two binary inputs of all-optical AND gate are modulated by return to zero and non-return to zero (NRZ) modulation formats. The quality factor (Q-factor) has been examined on the basis of critical parameters of SOA. The obtained results show that the acceptable Q-factor (>6) is possible with the proposed design at input signal power even as low as 50 μW (−13 dBm), when the data is modulated in NRZ on-off keying (OOK) format.

Using two nonlinear photonic crystal ring resonators we proposed and designed an all optical decoder. 2D 12 fold quasicrystal was used as the core section of the resonant rings. In order to make use of advantages of nonlinear Kerr effect, we put 24 dielectric rods between the core and outer shell of the resonant ring. The linear refractive index and nonlinear Kerr coefficient of these rods are n 0  = 1.4 and n 2  = 10 −14  m 2 /W. In the proposed structure port I was used to switch the optical beams coming from BIAS between O 1 and O 2 output ports. The optical intensity required for performing the switching task is about 0.1 kW/μm 2 .

Data centers are facing huge bottlenecks due to the emergence of high-speed data applications. To meet speed requirements, it is proposed to shift the current technologies toward optical communication-enabled data center (DC) devices. This paper discusses the recently proposed optical switch designs and proposes a novel switch design for optical DCs. The architectures proposed in the literature are compared in terms of notable parameters. Finally, proposed switch performance is measured in the network using Monte Carlo simulation and results are obtained in terms of packet loss probability, under a random traffic model while considering both nonperiodized and prioritized packets.

Optical packet switching (OPS) exhibits the ability to be utilized as a data transmission technique for next-generation. The core router/switch plays a significant role in packet routing and buffering in OPS. Arrayed waveguide grating (AWG) is realized as a promising core element for fast optical switching, with its intrinsic capacity to achieve wavelength routing of different wavelengths in parallel. This paper proposes an AWG-based add-drop optical packet switch, including a hybrid buffer, to resolve contention among packets. In a hybrid buffer, both optical and electronic buffers are used for the buffering of contending packets. AWGs are affected by crosstalk that can significantly impair system operation. The physical layer analysis is discussed in the presence of crosstalk, and the performance of the switch is evaluated in terms of bit error rate. The desired minimum input power is calculated for the switch’s correct operation for both optical buffer and electronic buffer. Finally, the packet loss probability (PLP) of the hybrid buffer is examined under various buffering conditions. Results reveal that with the increase in the optical power of the input signal, crosstalk power increases linearly for optical and electronic buffers. The increased crosstalk power is higher for electronic buffers than the optical buffer. The use of electronic memory in the hybrid buffer allows the hybrid buffer to increase its buffer size thus, reducing the PLP.

Due to the evolution of data centric applications demand for high speed data transfer and more bandwidth is increasing continuously. The unavailability of components like tunable wavelength converters (TWCs) restrict the transfer of parallel information using wavelength division multiplexing (WDM), therefore in the present scenario optical orthogonal frequency division multiplexing can be used. Moreover in optical communication narrow Gaussian pulses are transmitted, which spread with distance and leads to the broadening of the pulse and pulse peak power goes down and thus limits the system. In this paper a Soliton based optical communication system is proposed and its comparison with Gaussian pulse is presented and it has been found that soliton pulse has lesser bit error rate in comparison to Gaussian pulses.

A linearization scheme is proposed for microwave photonic link to enlarge spurious free dynamic range using a dual-electrode dual parallel Mach–Zehnder modulator (MZM). This scheme employs phase control method to improve performance of the link by adjusting phase of radio frequency (RF) signals and bias voltages of optical modulator. Optical single sideband modulation is achieved through sub-modulators of dual parallel MZM which increases efficiency of the link. The simulated results show that third order intermodulation distortion is suppressed by 28 dB when the input RF signals are 9.1 and 9.5 GHz and noise floor is at −161 dBm/Hz. The spurious free dynamic range is also improved by 12.6 dB.

An all optical comparator is designed based on photonic crystals. The proposed structure was designed based on optical threshold switching that is realized using three nonlinear ring resonators. All nonlinear rings have the same optical characteristics, such that they can drop low intensity (as low as 0.5 W/μm 2 ) optical waves at 1550 nm, but cannot drop the optical waves with optical intensity of 1 W/μm 2 . For the proposed structure the rise and fall time are about 2 and 1 ps, respectively. Therefore the bit rate is about 167 GHz and the ON/OFF contrast ratios for O1, O2, and O3 are 13.5, 13.6, and 13.3 dB, respectively.

In this work, the authors investigate the new structure of all optical half subtractor in a two dimensional photonic crystal based on wave interference and phase shift keying technique. The suggested structure is designed using 10 optical waveguides and one defect in the basic structure. The numeral methods such as plane wave expansion and finite difference time domain are used to analyze the proposed structure. According to obtained results, the rise and fall times, the working bit rate, the minimum and maximum values of the normalized power at ON and OFF states for output ports are 0.1 ps, 0.05 ps, 5 Tbit/s, 77 and 17%, respectively. According to results, high switching speed, compactness, low power consumption and ultra-fast operation are the main advantages of designed optical half subtractor compared with the previous structures.

Ultrafast all optical computing is getting attention for future generation services and all optical logic gates are basic building block for the photonic circuits in processing units. In this work, a multi-input single-output all optical AND/NOR gates are proposed using dispersion compensation fibers in Mach-Zehnder configuration (DCFs-MZI). Four wave mixing effect emerges in DCF and due to Kerr’s effect, aforementioned gates are realized at 10.2 Gbps. A low power logic gates with >23 dB extinction ratio are achieved and performance analysis is performed in terms of Q factor.

In this paper, analysis of tunable optical filter based on Sagnac effect tuning is presented using a fiber-optic ring resonator (FORR) and the responses of the filters for different FORR and Sagnac loop parameters under steady-state conditions are investigated. Formulation of the optical filter response is presented by considering with/without single and multiple Sagnac loop effects. Effects of the FORR parameters of filter response are studied and analyzed under different parametric conditions for the maximum transmission intensity. The simulation results show that the filter responses are affected strongly by the Sagnac loop and the FORR parameters. With the Sagnac effect, it is shown that full-width at half maximum (FWHM) would increase by increasing the phase difference Δ ϕ from 0 to 0.20 radian, beyond which it will start decreasing. The difference in FWHM value in this range of Δ ϕ variations is found to be about 3.77 nm. Between the first and the second resonances at wavelengths 1395 and 1538 nm, the free spectral range (FSR) is found to be 140 nm. In multiple loops effects, by increasing the number of loop turn N , the values of FSR would reduce. For Δ ϕ  = 0.3 and N  = 1,  2,  3, the values of FSR are obtained as 144, 74, 47 nm, respectively.

Spectral Amplitude Coding-Optical Codes Division Multiple Access (SAC-OCDMA) is a future multiplexing technique that witnessed a dramatic attraction for eliminating the problems of the internet in optical network field such as multiple-user access and speed’s growth of the files or data traffic. In this research article, the performance of SAC-OCDMA system based on two encoding–decoding multidiagonal (MD) and Walsh Hadamard (WH) codes is enhanced utilizing three different schemes of dispersion compensating fiber (DCF): pre-, post- and symmetrical compensation. The system is simulated using Optisystem version 7.0 and Optigrating version 4.2. The performance of the proposed system is specified in terms of bit error rate (BER), Q-factor and eye diagram. It has been observed that the compensated system based on MD code is performs much better compared to the system based on WH code. On the other hand, the compensated SAC-OCDMA system with symmetrical DCF has the lowest values of BER and largest values of Q-factor, so it is considered the best simulated scheme contrasted with pre- and post-DCF.

The multicore fibre (MCF) is an effective and auspicious technology to overawe the limitation of the single-mode fibre. One of the important applications of MCF is power over fibre. In this paper, we have been designed eight different hexagonal structures by using 6, 7, 8, 9, 10, 11, 12 and 13 cores MCF. Those designs are categorized as even core multicore fibre (ECMCF) for 6, 8, 10 and 12 cores and odd core multicore fibre (OCMCF) for 7, 9, 11 and 13 number of cores. We also studied the impact analysis of odd or even number of the cores. The proposed designs having 140 µm diameter, large effective area of 1256 µ 2 m and two pitches d 1 =20 µm and d 2 =10 µm. The comparative analysis has been done by core multiplicity factor, electric field, coupled power, cross overpower parameter calculated for 10,000 samples. The hexagonal core shape MCF shows better performance if the number of the core in even number.

This review paper scrutinizes the staging of dense wavelength division multiplexing soliton system in return to zero and non-return to zero format. In-line optical phase conjugator (OPC) is used to depreciate the power of four wave mixing (FWM). Destructive interference between both the halves of in-line OPC plummets the FWM power sturdily. This paper concludes with the indication that return-to-zero with OPC gives out better performance with FWM suppression.

Stimulant abuse enhances dopamine release, thereby causing increased excitation. Any extent of stimulant abuse can considerably harm the user. Thus, methods of detecting stimulants must be precise, accurate, and reliable. A novel terahertz (THz) photonic crystal fiber with a Topas substrate is designed and rigorously investigated for detecting liquid amphetamine, cocaine, and ketamine. The fiber structure has a pentagonal shape and comprises circular air holes in the core and cladding spatial extents. As shown in finite element simulation, the proposed fiber yields a high relative sensitivity of approximately 80 % when any of the liquid stimulants is infiltrated in the core air holes. At 1 THz operating frequency, the proposed fiber produces a large effective mode area, negligible confinement loss, and extremely low bending and effective material losses. Other THz waveguiding properties, such as core power fraction and total loss, are also studied. Lastly, a positive and negative 2 % fabrication tolerance is set to ensure seamless potential practical realization of the fiber.

In this paper by using modified scalar effective index method, first effective refractive index of straight and bent photonic crystal fibers are determined and then propagation parameters, such as chromatic dispersions for different structural designs of PCF, are obtained. By changing the values of affecting parameters in the bent PCF, such as different bent radius, distance between air holes Λ $\Lambda $ and air-filling factor d / Λ , $d/\Lambda ,$ the chromatic dispersion is determined in terms of propagating wavelengths. The obtained results of bent PCF are compared with the results of straight PCF. The results of the present paper might be useful in designing optical devices and sensing systems.

In the current study, a novel Zeonex based porous core photonic crystal fiber (PC-PCF) is presented for polarization-maintaining and dispersion flattened in the terahertz (THz) region. For minimizing the Effective Material Loss (EML), an array of three rectangular and six triangular air holes are surrounded by hexagonal-shaped cladding. Finite Element Method (FEM) is employed through Comsol V5.3a software to design and examine the essential features of the proposed porous core fiber which revealed that it has an extremely small EML of 0.04 cm −1 at 1.2 THz and has almost zero flattened dispersion of 0.8 ± 0.08 ps/THz/cm in 1.0–1.4 THz frequency spectrum. Moreover, the optimum designing parameters offer an extremely high value of birefringence (0.043 at 1.2 THz). Besides, other major features notably bending loss, effective area, and confinement loss are also found to be precise and relatively low. For effective, adaptable and fitting transmission characteristics, this type of design would lay the foundations for broadband THz radiation wide variety of usage in the THz regime.

In this study, design and transmission characteristics of a special type of photonic crystal fiber (PCF) geometry namely, circular-lattice photonic crystal fiber (C-PCF) structure are presented. The cladding of the structure consists by a cylindrically symmetrical distribution of air-holes in the silica background and the core is created by omitting one air-hole at the center. The structure provides high degree of flexibility in the fiber design and hence tailorable modal properties. Structural dependence of transmission characteristics of the geometry is numerically investigated by using finite difference mode convergence algorithm. The wavelength responses of fiber parameters, such as effective refractive index, chromatic dispersion, mode-effective area, and nonlinear coefficient of the structure are systematically investigated. Besides, effective V-parameter and single-mode operation of the fiber are also evaluated and discussed. The simulation results show the possibility of large negative dispersion and dispersion flattened nature of the geometry.

A four-ring microstructure photonic crystal fibre with a descending air hole ring cladding is presented. Numerical analysis of the structure is done using full vectorial finite element method with perfectly matched layer (PML) boundary condition. It is demonstrated that it is possible to achieve at 1.55 µm confinement loss of 2.767 × 10 −5  dB/m, birefringence of 0.00346 and a nonlinear co-efficient of 41.77 km −1  W −1 . Also, chromatic dispersion realised suggests a tuneable zero dispersion at 0.9–1.1 µm wavelength range.

We propose and numerically demonstrate chalcogenide based bend M-type fiber for mid-IR supercontinuum (SC) generation through higher order mode (HOM) of LP 02 . In order to achieve this, we comprise two glass materials such as As 2 Se 3 in core and Ge 10 As 23.4 Se 66.6 in cladding. M-type index fiber has a special property that the HOM of LP 02 is confined into the core region with help of high index ring. The mode field distribution of the proposed fiber is numerically calculated by a finite element method. By optimizing structural dimensions in each bending case, we realize a zero dispersion wavelength, double zero dispersion wavelength effective area and power fraction in core. The simulation results shows the flat anomalous dispersion in the wavelength range of 2.1–2.6µm and 2.5–6.5µm for the core radius 4 and 10 µm, respectively at bending case of 1, 3, and 5 cm. which is important for employing the mature fiber laser technology at mid-IR regions.

Wireless communication are becoming as a part of human life. If we want to achieve the efficient and affordable communication in wireless technology in optical domain, stable signal and ultra-low phase noise is required. Optoelectronic oscillator is based on converting continues light energy in stable and low phase noise, high-quality (Q) factor is used in wireless communication. If quality factor is low, then the oscillation dies out rapidly. Delay line is used provided higher-quality factor that is used. There are numerous techniques for the photonic generation of microwave signal with high time-bandwidth product and low phase noise. Optoelectronic oscillator (OEO) based generation techniques have been found one of the most interesting technique since last three decades. This approach provides very high frequency microwave signal with lowest possible phase noise. OEO has been designed with miscellaneous architecture by introducing different optical dispersive components such as optical fiber, chirped fiber Bragg grating, polarization modulator, and ring resonator. In this paper, numerous techniques for the design of OEO are reviewed and well demonstrated. There are interesting configurations with substantial improvement in phase noise and frequency of the microwave signals generated. MATLAB simulation has been used for the verification of result explained in this technique.

In this paper, the rigorous derivations of generalized coupled chiral nonlinear Schrödinger equations (CCNLSEs) and their modulation instability analysis have been explored theoretically and computationally. With the consideration of Maxwell’s equations and Post’s constitutive relations, a generalized CCNLSE has been derived, which describes the evolution of left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) components propagating through single-core nonlinear chiral fiber. The analysis of modulation instability in nonlinear chiral fiber has been investigated starting from CCNLSEs. Based on a theoretical model and numerical simulations, the difference on the modulation instability gain spectrum in LCP and RCP components through chiral fiber has been analyzed by considering loss and chirality into account. The obtained simulation results have shown that the loss distorts the sidebands of the modulation instability gain spectrum, while chirality modulates the gain for LCP and RCP components in a different manner. This suggests that adjusting chirality strength may control the loss, and nonlinearity simultaneously provides stable modulated pulse propagation.

We propose a perfectly square lattice photonic crystal fiber (PCF) which shows high birefringence and negative dispersion. To set up high asymmetry in the core, dual line imperfection is considered where the fill fraction ratio and defect air hole diameter exhibit significant impact on dispersion and birefringence. Numerical analyses of guiding properties of the proposed PCF are done using finite element method with perfectly matched layer boundary condition from 1.2 to 1.8 μm wavelength. The optimized square lattice PCF presents high birefringence of 2.48 × 10 −2 and dispersion of −777.66 (ps/nm.km) at 1.55 μm wavelength. In addition, the proposed PCF offers ultra-low confinement and insertion loss at 1.55 μm wavelength. Moreover, −0.45 (ps/nm 2 .km) dispersion slope and 0.0045 nm −1 relative dispersion slope are observed at 1.55 μm wavelength. Additionally, the proposed PCF maintains dispersion and birefringence variation of ±30 (ps/nm.km) and ±0.00001 between 1.5 and 1.6 μm wavelength ranges, respectively. Furthermore, the proposed PCF shows high quality factor and low bit error rate at 10 dBm input power. We believe the proposed square lattice PCF can be deployed in wavelength division multiplexing based optical fiber transmission system for wide-band dispersion compensation.

An AlGaAs based standard photonic crystal fiber structure is reported for low dispersive nonlinear optics applications. By employing a finite element solver with perfectly matched layer boundary condition, the key propagation characteristics are investigated over a broad wavelength span (1–5 μm) by taking the different air filling fraction values. The proposed work provides an effective fundamental mode area of 7.30 μm 2 with nonlinearity in the order of 8.325 W −1 m −1  at a low absorption wavelength of 1.55 μm and zero-dispersion wavelength close to 3 μm.

In this work, a dispersion compensating photonic crystal fiber (DC-PCF) is proposed in which dispersion, dispersion slope, second order dispersion, third order dispersion, nonlinearity, effective mode area, V parameter are investigated. The suggested structure is very effective for compensating of chromatic dispersion about −951 to −3075.10 ps/(nm.km) over 1340–1640 nm wavelength bandwidth. With perfectly matched layer boundary condition, guiding properties are inspected applying finite element method (FEM). The investigated results conform the opportunity of large negative dispersion and high group velocity dispersion (GVD) of −2367.10 ps/(nm.km) and 3018.55 ps 2 /km respectively, at 1550 nm operating wavelength. The offered fiber also shows low third order dispersion about −637.88 ps 3 /km, high nonlinearity of 91.11 W −1  km −1 . From overall simulation results, it can be expected that the suggested PCF will be an effective candidate in high bit rate long haul optical communication system as well as sensing applications.

In this paper, the dispersion characteristics of two standard single-mode optical fibers (SMFs), fabricated with silica and poly (methyl methacrylate) (PMMA) are studied in telecommunication spectral regions. The effect of structural parameters, such as the radius of the fiber core and the relative core-cladding index difference, is numerically investigated. It is found that over whole spectral range, the PMMA-based SMF shows lower dispersion than the silica SMF. Also, the zero-dispersion wavelength (ZDW) of PMMA-based SMF is longer than that of silica fiber. The results may be of practical importance for the telecommunication applications.

This paper reports simple but accurate analytical expressions of group delay and modal dispersion parameters for single-mode graded index fibers over a wide range of V numbers. The formulation employs power series expression for the fundamental modal field of graded index fiber derived by Chebyshev formalism. Choosing some typical step, parabolic and triangular index fibers as examples in our present study, we use the prescribed formulations to estimate group delay and modal dispersion parameters of those fibers both in presence and absence of Kerr nonlinearity. Iterative technique is applied for prediction of concerned propagation parameters in presence of Kerr nonlinearity. Our results show excellent agreement with the numerical exact ones both in absence and presence of Kerr nonlinearity. The exact results in case of Kerr nonlinearity are obtained using cumbersome finite element method. The execution of our accurate formalism involves little computation and is thus user friendly for technologists and researchers working in the field of nonlinear optical engineering.

A new type of high birefringence terahertz (THz) band photonic crystal fiber (PCF) is proposed. D-shaped air holes are introduced into the core of the PCF and the cladding near the core. Some important parameters of this waveguide were researched in the range of 0.6–1.2 THz. The simulation results show that the proposed fiber has a high birefringence of 0.0425 at 0.7 THz. In addition, the confinement loss and the effective mode area are respectively 6.63 × 10 −7  dB/m and 0.77 × 10 5  μm 2 , when the operating frequency is 1 THz and the high birefringence of 0.04 is maintained. At the same time, very low bending loss and near zero flat positive dispersion are obtained. And has single-mode operating characteristics in the entire research frequency range. The PCF structure will provide new solutions for the application of THz waves and the design of THz waveguides.

This analysis represents a circular shape based cladding with two elliptical shape cores in photonic crystal fiber (PCF) for the terahertz (THz) range. Here, we present a single-mode photonic crystal fiber (SM-PCF) with five layers of circular shape of air holes (CAH) structure along with two layers of elliptical shape of air holes (EAH) core configuration in the center to decrease the different types of losses. For broad-band communications, our proposed SM-PCF is highly useful due to the obtaining of ultra-low effective material loss (UML) in the terahertz regime. Perfectly matched layers (PMLs) and finite element method (FEM) established on COMSOL Multiphysics software has been used to design this PCF fiber. Simulated outcomes show a particularly an UML deficit of 0.014 cm −1 , power fraction in the core area (CA) and large effective area (EA) of 72%, and 5.90 × 10 −8  m 2 respectively at 1 terahertz (THz) frequency. Also, other aspects of optical fiber for THz signal banquet with confinement loss (CL), scattering loss (SL) and V-parameter have been calculated here. Moreover, our proposed SM-PCF shows single-mode propagation by V-parameter pointer over 0.80–3 THz frequency. So, we can say that our designed PCF fiber will be suitable for various effective communication areas at the terahertz (THz) spectrum.

In this work, the effect of mixed beta and gamma radiation on the optical fiber properties was investigated, this effect has been studied for different signal frequencies which range 1–100 kHz carrying on laser beam using amplitude shift key (ASK). Single mode (SM) glass optical fiber was utilized, and exposed by (Cs-137) as radioactive point source with different low dose rates. The variation of received optical power ( P r ), peak to peak voltage ( Vp-p ), voltage gain ( A v ), and signal to noise ratio (SNR) were measured before and after irradiation. It was observed that an improvement in the received signals which propagates in optical fiber after irradiation by exposure of lower dose rates.

In this paper, author has presented design strategies for two core uncoupled heterogeneous multi-core fiber (MCF) to achieve minimum crosstalk. Authors have studied the variation of crosstalk between the cores in respect to the MCF parameters like bending radius, wavelength, core position and fiber length, so that single mode propagation can be made through designed uncoupled heterogeneous cores. The other important performance parameters of MCF i.e. group delay and dispersion have also been discussed in the paper.

This work simulate the raised Cosine impulse function with Hamming grating profile based chirp Bragg grating fiber. The transmittivity/reflectivity, the grating ref index of the chirp grating fiber variations, real/imaginary coupling coefficient variations and the cross section monitor of the mesh transmission variations are simulated and clarified versus the length of grating. The transmission/reflection spectrum, input grating pulse width intensity spectrum, and the output grating pulse width intensity against the grating wavelength are demonstrated clearly. All the obtained results are demonstrated with the OptiGrating simulation software version 12. The transmittivity/reflectivity of chirp grating fiber, the grating ref index of chirp grating fiber, the cross section monitor of the mesh transmission and the real/imaginary coupling coefficient variations are simulated and demonstrated against the grating performance parameters.

In this paper, a graded-index metamaterial (GIM) nanostructured waveguide is proposed to enhance the performance of solar cells via a tunable absorption spectrum. The proposed four-layer nanostructured waveguide consists of two GIM and SiN x films which are squeezes between glass substrate and air. Using a transmission matrix method, the transmittances as well as the reflectance are calculated for different film thicknesses, refractive indices and incidence angles. We demonstrate that the reflectance is nearly zero where SiN x refractive index is 2.2 in vicinity of 620 nm. As the incident angle increases, the minimum reflectance wavelength blueshifts and slightly increase in the value. In addition, the variation in the minimum reflectance due to a change in the thickness of SiN x layer studied in detail. We show that the absorbance of a solar cell can be easily controlled by varying refractive index and/or thickness of SiN x layer in the proposed nanostructure. The result shows that the best efficiency occurs at normal incidence, n 2  = 2.2, and d 2  = 30 nm.

A chaotic synchronization based on mutually coupled different semiconductor lasers and its coding communications are studied. A route to chaos is illustrated by a bifurcate diagram. Chaotic distribution is presented in two lasers. The synchronization equation is given in theory. A chaotic synchronization is obtained between the emitter and the receiver. Other complex dynamical behavior synchronizations are also obtained, such as period-5 and period-10 synchronizations. Cascade synchronizations are achieved. A novel On/Off coding system is presented while its chaotic phase encoding is successfully implemented. Chaos key is also numerically simulated. We find that synchronization can still be achieved when the parameter of the emitter changes at any time so that the newly generated chaotic carrier can ensure mask the information in each communication. Then the real-time variable parameter results in difficulty for eavesdroppers to decipher. Compared with a single laser emitter, this emitter has many secret keys and high security, which is beneficial to its potential application in secret communication.

Optical frequency comb (OFC) sources, for their highly desirable properties, they have revolutionized a wide range of applications specifically orthogonal frequency-division multiplexing (OFDM) system. OFC sources based on femtosecond erbium fiber laser has emerged as the most commonly used in many applications owing to their advantages of low cost, robustness, compactness, high performance, and flexibility. Here, 300 fs soliton mode-locked pulses were achieved using erbium fiber oscillator based on an efficient Graphene saturable absorber and an external all-fiber pulse compressor consisted of erbium-doped fiber amplifier (EDFA) and 200 m long single-mode fiber (SMF). The proposed system works with a central wavelength of 1557 nm at the desirable communication band. The output power of the system and its corresponding pulse energy were 9.29 mW and 1.858 nJ, respectively, at a maximum pump power of 92.6 mW. The designed system is entirely fiber based, with no free-space optics and uses only standard telecommunication equipment. The results of this experiment demonstrate that the simple design of mode-locked fiber oscillator with an external compressor can provide a compact, portable, robust, reliable and high-performance femtoseconds frequency comb.

In this work, we propose a new filter design based on a ring resonator. This structure has 99% transmission ratio and high sensitivity to detect small refractive index variations of the order of 0.002. More specifically, the small size of this resonator gives the advantage to model a demultiplexer of size 463 µm 2 based on four ports which operates in the conventional transmission band. Also, we show that our demultiplexer structure can reach more than 90% transmission ratio with an optical quality factor of about 3800, the spectral width is 0.72 nm and a crosstalk between −13.28 and −32.13. In our study, we emphasized the plane wave method to study the photonic band gap and FDTD to determine the transmission spectrum.

Different types of laser source modulation techniques have been used in various applications depending on the objective. As optical systems extract the laws and the best solutions from experiments and simulations, the present study uses simulation software with different modulation types so the output signals can be compared. The modulators used are Mach-Zehnder, which is an external modulator, and electro-absorption modulator and laser rate equation modulator, which are direct modulators. All these types have an optical link multimode (MM) fiber with a photodiode in the receiver end that can be modeled. The input and output signals are analyzed using different types of modulations.

This paper presents measurement of third order intermodulation distortion and third order intercept (TOI) in a Fabry–Perot semiconductor laser lasing at 1550.3 nm when the laser is biharmonically bias-current modulated. Keeping the modulation current of one signal fixed, the third order intermodulation power at two different frequencies has been found to increase with the increase in second signal modulation power. There is an eventual crossover or tendency to crossover in the intermodulation characteristics when the modulation current amplitudes of the channels assume the same value. The TOI has been experimentally measured. The intermodulation power appearing at two different frequencies along with their signal power dependence and measurement of TOI constitute the outcome of this paper. The typical value of spurious-free dynamic range of the modulation scheme is 70 dB.

Chaos synchronization of two quantum dot light-emitting diodes (QDLEDs) theoretically is studied, which are via a closed or open-loop and mutual coupling system. Whereas the synchronized-chaotic systems, the dynamics of there are identical to uncoupled dot light-emitting diodes (DLEDs) under optical feedback effect. Complete synchronization was obtained under certain conditions for the coupling parameters. We evaluated the range of the QDLED’s chaos with extrinsic optical feedback in methods of the chaos synchronization residue diagram and discussion as well as the coherence for the optimal coupling strength range. With proper conditions of the coupling parameters and the evaluation methods, the synchronization was satisfactorily obtained between the transmitter and receiver.

We use ABCD matrix formalism for estimation of the coupling optics involving laser diode to cylindrical lensed circular core graded index fiber excitation. The investigation has been carried on for some typical step, parabolic, and triangular index fibers as examples of graded index fiber. It is relevant to mention in this connection that we have shown that the coupling optics is excellent along the vertical plane only while the coupling along the horizontal plane produces poor performance. Analytic expressions for coupling efficiencies are prescribed. The investigations have been made for two commonly used wavelengths, namely 1.3 and 1.5 µm. Our formulations require little computation for the necessary execution. The wavelength of 1.3 µm has been found to be more efficient in respect of coupling. Our formalism takes care of the limited aperture allowed by the cylindrical lens and thus provides the realistic prediction of coupling optics. The results will prove extremely useful to the designers and packagers working with cylindrical microlens.

The exponential rise in the demand for channel bandwidth over the last few years has lead to the problem of spectrum congestion in conventional radio frequency (RF)-based wireless communication systems. Radio over free space optics (RoFSO) provides an effective solution to tackle the problem of spectrum congestion due to its many merits including license-free bandwidth, quick and low-cost installation, cost-effectiveness, and highly secure transmission links. The high-speed data transmission capabilities and immunity to electromagnetic and RF interference makes it a suitable candidate for the development of future 5 G networks. This work focuses on the designing and performance analysis of 10 Gbit/s–10 GHz orthogonal frequency division multiplexing (OFDM) based RoFSO link under the impact of different environmental effects. Also, the performance of the proposed RoFSO link has been compared for different modulation schemes viz. optical dual sideband (ODSB) and optical single sideband (OSSB). Further, we propose an enhanced detection technique deploying Square root module (SRm) at the receiver terminal for link reach enhancement under the impact of adverse weather conditions.

We theoretically demonstrate an ultra-compact plasmonic modulator and switch of sub-micron size using elasto-optic effect with quite acceptable modulation ratio. The device is based on metal-dielectric-metal waveguide structure and uses resonance phenomena. The modulation mechanism originates by electrically changing thickness of dielectric layer made of elasto-optic material, which changes the effective refractive index of propagating optical mode. All the results are obtained using FEM simulation software. The seamless integration of optical beam modulation bears significant potential towards broadband, compact and efficient communication links and circuits.

Free-space optical (FSO) communication system provides several advantages over radio frequency (RF) system offering high bandwidth, low cost, small space requirements and more secure transmission which is free from Electromagnetic Interference (EMI). However, when the transmitted light signal passes through the atmosphere it experiences attenuation and fluctuations due to atmospheric turbulence. This paper analyzes the bit error rate (BER) performance of FSO communication systems under strong atmospheric turbulence for on-off keying (OOK), binary phase-shift keying (BPSK), differential phase shift keying (DPSK), quadrature phase shift keying (QPSK) and 8-phase shift keying (8-PSK) for link distances of 500, 1,000, 1,500 and 2,000 m. The probability density function (pdf) of the received irradiance is modelled using the gamma-gamma distribution model. It is found that the system exhibits the best BER performance and compensates the lowest power penalty at BER of 10  - 9 for BPSK modulation compared with other modulation techniques which makes BPSK more appropriate to be used with FSO turbulent system.

Generalized multiprotocol Label Switching (GMPLS) is a set of rules which is used in various layers like the Wavelength Division Multiplexing (WDM) layer, Time Division Multiplexing (TDM) layer, etc. to generalize the concepts of labels of Multiprotocol Label Switching networks. A block in call occurs when number of requests is more than the servers and waiting rooms. This call blocking is the very important parameter and can be calculated in terms of probability. There are a number of models to calculate the call blocking probability like Erlang B, Erlang C, etc. This paper suggests a novel, efficient and less – complex model which minimize the call blocking to very much extent for GMPLS networks. This model deals with the factors like number of wavelengths, number of links, traffic intensity, etc. which can help in reducing the call blocking probability and give better results. In this paper, the call-blocking probability is also compared with number of links by considering different wavelengths. A comparison of call-blocking probability of proposed model is also analysed. This paper deals with blocking probability optimization in GMPLS Networks using Fredericks approach. We have used peakedness factor from Fredericks approach in Engset’s formula for this optimization.”

For the effective bearer of P2P-type services, a P2P service bearer reorientation method for passive optical network for long-distance wide access based on P2P protocol message and wire-speed message identification is proposed. However, the reorientation method still has the possibility of relocation failure, so it is modified – that is, an improved P2P service bearer reorientation method based on optical line terminal (OLT) and optical network unit (ONU) cooperation. And the tool NS2 is used for network simulation analysis. Through simulation analysis, it is verified that the modified reorientation method improves the data traffic burden at the core network and at the OLT.

Physical layer impairments (PLIs) is a matter of great concern in optical networks to achieve the optimum performance. In order to mitigate the PLI, a better routing and wavelength assignment (RWA) technique is required in optical wavelength division multiplexing (WDM) networks. In this paper, a dynamic ant colony routing algorithm with the consideration of various PLIs has been presented. This work also presents a Q-factor estimation model that includes impairments such as amplified spontaneous emission (ASE) noise, four-wave mixing (FWM), and cross phase modulation (XPM). The simulation results also prove that the proposed ant colony optimization (ACO) based algorithm significantly reduces the blocking probability as compared to dynamic load based shortest path algorithm (LB-SPA).

Orthogonal frequency division multiplexing (OFDM) is a special form of multicarrier (MC) modulation technique which is adopted in 4G mobile communication systems. The combination of OFDM with passive optical network (PON) architecture is highly desirable for design of flexible and energy efficient backhaul and backbone networks for 5G systems. An intensive mathematical model for linewidth analysis in OFDM based backhaul (BH) and backbone (BB) systems is proposed. The proposed mathematical model includes fiber dispersion, fiber nonlinear effects, amplified spontaneous emission (ASE) noise, transmitter and receiver noises. The impact of laser linewidth in the developed analytical model is analysed in terms phase rotation term (PRT) and inter-carrier interference (ICI) power. Further, the BER performance of the DD-OFDM system as a function of laser linewidth is also presented. The results of the analytical model solved using MATLAB is compared with virtual photonics integrated (VPI) based simulation results. The results of our proposed model suggest that DD-OFDM would perform better for lower linewidth in dispersion uncompensated (DUC) links and it has no impact on the dispersion compensated (DC) links for BB networks. In BH networks, the system performs better for lower linewidth in both DUC and DC links.

Radio over fiber plays a prominent role in the realization of next generation integrated Optical -Wireless Networks to distribute mobile broadband signals effectively to meet the increasing demand of multimedia services with guaranteed quality of services. In this paper the signal transport schemes of analog and digitized Radio over fiber systems with relevance to cellular communication and the comparison of different Radio over fiber systems with their merits and demerits is explored. Further, review of existing different types of multioperator multiservice architectures to realize high performance Radio over fiber based fronthaul architectures also presented in detail.

The growth of optical technology is currently being studied extensively to meet the significant demand for bandwidth. The passive optical network (PON) solves the problem of bandwidth as it extends the optical network to individuals and businesses [Sifta R, Munster P, Krajsa O, Filka M, “Simulation of bidirectional traffic in WDM-PON networks", Brno University of Technology, ISSN 0033–2097, R. 90 NR 1/2014.]. In this paper, a comparative study is made between the WDM PON system and the CWDM PON system using two different architectures, one for the WDM PON and the other for the CWDM PON, to illustrate the appropriate technique for the PON network by increasing the Q factor and the OSNR ratio while minimizing the bit error rate ( BER < 10 –9 ). Both systems are simulated at 10 Gbps for four users of bidirectional SMF (Single Mode Fiber) fiber lengths and different powers. In order to determine the transmission performance for both systems, the link was designed for fiber lengths of 20, 30, 40, 50 and 60 km as well as for powers from −10 dBm up to 10 dBm for four users. The use of the EDFA amplifier in the WDM PON system is required in this document to minimize degradation caused by attenuation [Parkirti RDK, Singh R. Cost-efficient Colorless WDM-PON Based on RSOA for High Capacity. Int J Adv Res Comput Eng Technol (IJARCET). 2016;5]. On the contrary, in the CWDM PON system, the amplification is not essential because the wavelengths used in this system are not affected by the water peak which causes a strong attenuation of the wavelengths in the 1370–1410 nm range on optical fibers [Nazir M, Arshad F, Asif R. Design and evaluation of power budget for a bidirectional CWDM-Passive Optical Network. In: International Conference on Communication, Computing and Digital Systems (C-CODE), Islamabad, Pakistan, 04 May 2017.]. The peak of water vapor absorption is close to 1383 nm.

The paper outlines the divergence of beam and operating wavelength bands effects on free-space optics communication channels in local access networks. The max Q factor and min bit error rate are measured based on the divergence of beam and operating wavelength bands variations. The signal is tested also at the receiver side by using an optical power meter visualizer at various operating signal wavelength bands and under the optimum values of the divergence of the beam. The study has presented the optimum operating conditions for upgrading network operation efficiency.

Visible Light Communications (VLC) is considered as an emerging technology for indoor wireless communications to achieve high-speed and secure data transmission. Instead of using radio frequency (RF) spectrum, VLC uses the visible light spectrum to perform lighting and communications functions simultaneously. Multiple access points VLC (multi-AP VLC) networks use ceiling access point (ceiling-AP) and desk access point (desk-AP) to provide both uniform and spot lighting in order to achieve full coverage and high spectral efficiency. Because mobile user equipment (UE) require seamless connectivity when moving, fast link handover between VLC access points (VLC-AP) has to be supported in the VLC networks. In this paper, we present a coordinated multi-channel transmission method (CMcT) used to improve quality of service (QoS) of cell-edge UEs and propose a novel proactive link handover scheme deploying the CMcT method for multi-AP VLC networks. Performance results obtained by computer simulation show that the proactive link handover scheme deploying the CMcT method can significantly improve user throughput and packet delay comparing with those of other link handover schemes.

Bandwidth assignment is a key issue in optical access networks, so an efficient mechanism is required for dynamic distribution of limited resources in the uplink channel among competing subscriber optical network units (ONUs). This paper presents a novel optimized dynamic bandwidth allocation (ODBA) algorithm for hybrid WDM/TDM passive optical networks. ODBA algorithm operates using information frame length of the subscriber’s ONUs and their information arrival rate; both of these factors finalize the assigned transmission capacity to the users. The system performance under differing offered traffic loads is evaluated in terms of network throughput, average delay and channel utilization. Further, the proposed ODBA scheme is validated by performing a comparative analysis with well-known algorithms.

In data center networks use of optical communication has revolutionized the data transfer mechanism. Optical communication heavily relies on enormous bandwidth of optical fiber. Wavelength Division Multiplexing (WDM) technique can be used for utilization of huge bandwidth. To employ WDM which uses distinct set of wavelengths to carry data wavelength converters are required. However as the tunable range of wavelength converter increases both cost and technological design complexity rises exponentially. Therefore, both Limited Range Wavelength Converter (LRWC) and Full Range Wavelength Converter (FRWC) are considered. However, under higher loading conditions buffering is also required as using wavelength converter (WC) blocking can be reduced significantly. This paper presents comprehensive analysis of blocking performance under various types of wavelengths converters and buffering of contending packets.

The purpose of this study is to evaluate the impact of the location of the Er 3+ /Yb 3+ optical amplifier (EYDWA) in passive optical access network downstream (as a post-amplifier or booster, in the middle) and upstream transmission . This can give us an extended connection and a huge distribution ratio for a beneficial implementation of the optical fiber. The transmission quality was compared on the location of the amplifier as well as the length of the link. According to the results obtained by system simulation one noted that there is a clear improvement of the system performance by the effect of the amplifier (EYDWA). One could obtain a distance of more than 200 km for GPON. Moreover by varying the opto-geometric parameters such as concentration of Ytterbium ions and the length of the guide allowed us to improve the quality factor and binary error rate.

For the commercial wavelength division multiplexing passive optical network (WDM-PON) with standard single-mode fiber SSMF-28 and 1:64 passive fiber branching at its far end (RN) and 100 GHz C-band continuous wavelength (CW) lasers, the maximum coverage and optimal transmission power of STM-16 and STM-64 with external modulators at different speeds and wave numbers (4λ, 8λ and 16λ) are obtained, respectively. The performance parameter of the high data rate WDM-PON system is analyzed with respect to a number of channels and reach. In order to improve the network utilization and receiving efficiency, the influence of different channels and transmission distances on the performance of high data rate WDM-PON system is analyzed. Simulation analysis with Optisystem15.0. The maximum transmission power required to achieve the maximum transmission distance under the condition of nonlinear constraints is obtained. In order to save power consumption, the configuration of each multi-band PON is optimized in terms of transmission power. It is found that WDM-PON system has to compromise between aggregated data rate and system reach. Future software defined access network reconfigure the access network depending on the dynamic demand and the resources available. Hence depending on the distance between the optical line terminal (OLT) and optical network unit (ONU) guaranteed data rate can be estimated. ONU is equipped with a tunable optical filter (TOF) hence future wavelength can be reconfigured by both service provider and user. It makes it possible for software to customize optical access network.

Optical foundation suppliers and system administrators with another design are used to improve their conventional business activities toward a genuine start to finish cloud item contributions. Optical system suppliers will assemble a consistent foundation and rent it to arrange administrators; the last will work financial-savvy, dynamic and mission-explicit systems utilizing coordinated observation and the board methods. In light of this vision, our article will indicate and execute an IP-MSAN optical system engineering (installation + configuration) capable of supporting the provision of optical network and Unix/Linux platform server-based system resources and thus designing a true cloud infrastructure with heterogeneous/homogeneous servers. We will present the configuration script for a site with 750 subscribers in the Constantine city, Algeria.

An important problem of network traffic is how to efficiently carry massive amounts of data traffic generated by Peer-to-Peer (P2P) services in high-speed and large-capacity optical access networks. P2P file-sharing traffic is regarded as one of the biggest bandwidth consumption in the world. Internet service providers can reduce the bandwidth burden in the feeder fiber by localizing the network traffic. In this paper, we propose an enhanced redirection strategy based on the optimized MPCP protocol (ERS-MPCP) to redirect the traffic into the access network and reduce the latency. A Markov chain is used for mathematical modeling. In the proposed strategy, we build a simulation platform for network simulation. Simulation results show that our strategy can improve the overall redirection success rate by up to 9%, thereby reducing the data traffic burden on the core network.

For implementing wide/metropolitan area network in optical fiber communication system the key technology that can be utilized is wavelength division multiplexing (WDM). We discuss the use of WDM in metropolitan networks along with its special feature of using optical add drop multiplexers and also design issues in implementing these systems. The issue of nonlinear crosstalk induced in metropolitan networks is considered in terms of power penalty. Also, the effect of dispersion induced in optical fibers is considered by using two types of transmission systems. One is considering the non-zero dispersion shifted fiber (NZDSF) in dispersion effected environment and second is, implementing dispersion compensation after normal single mode fiber (SMF + DCF). The effect of nonlinear cross talk which can limit transmission performance is discussed in both cases in context with different parameters like power penalty, frequency difference between signal & crosstalk and transmission distance etc.

This paper investigates the impact of coherent and incoherent crosstalks on bit error rate of a multihop wavelength division multiplexing (WDM) transmission system with limited-wavelength-interchanging cross connects (L-WIXCs). The relation between the crosstalk and signal to crosstalk plus noise ratio at the receiver output is analyzed and redefined with an improved mathematical modeling. Quantitative analysis of the bit error rate (BER) in terms of system parameters like number of hops, number of fiber and number of wavelength channels per fiber are evaluated. The power penalty due to accumulated crosstalk at a given BER of 10 −9 and the optimum system design parameters are also determined numerically. Results show that there is a significant power penalty of the order of 10–12 dB due to accumulated crosstalk depending on the number of hops. Maximum allowable number of hops at a given BER of 10 −9 and number of input fibers are also evaluated.

Hybrid Optical Amplifier (HOA) has made a significant change in Wavelength Division Multiplexed (WDM) optical networks. We have proposed diverse hybrid optical amplifier configurations for the better performance of WDM optical networks. These configurations are SOA-EDFA, EDFA-EDFA and EDFA-Raman amplifier for 24 channels WDM optical networks at 10 Gbps with channel spacing of 0.8 nm. The performance of the systems is evaluated on the behalf of different parameters such as, quality factor, eye diagram, bit error rate and output power. The efforts are made to optimize these parameters. From the results, it is assessed that EDFA-Raman configuration gives superior results as compared to EDFA-EDFA configuration and SOA-EDFA hybrid optical amplifier configuration for long distance. Further it is also observed that EDFA-Raman hybrid optical amplifier configuration is suitable for high data rates up to 20 Gbps.

A novel differential mode delay (DMD) and modal bandwidth measurement technique for a multi-mode optical fiber based on time-domain method has been proposed and analyzed. Mode-dependent loss (MDL) is known to have a detrimental impact on the capacity of multi-mode fiber systems. The bandwidth behavior of 50 μm/62 . 5 μm graded-index multimode fibers (GI-MMFs) is investigated by launching a temporal pulse into the fiber and measuring the output time-domain waveform to understand and characterize the effect of DMD. The baseband response is measured by observing the broadening of a narrow input pulse (time-domain measurement). This paper verifies the degradation in bandwidth due to profile distortion by the maximum radial shift (starting from the center of the fiber) and the number of steps. The impact due to DMD on GI-MMF performance has been analyzed through fiber transfer function, pulse width and phase changes.

In this paper, we have presented the design and simulation of a 7-channel next-generation passive optical network (NG-PON2) network for the deployment of Fiber-to-the-X (FTTX) access network. Coexistence architecture is proposed, designed and simulated for the implementation of NG-PON2 access network. In a coexistence architecture approach, legacy PON networks like Gigabit passive optical network (GPON) PON, 10GPON, etc. and wavelength division multiplexing (WDM)-PON supporting point-to-point connectivity are designed and simulated together. A 4 × 4 WDM-PON in which each channel carrying data at 2.5 Gbps data rate is capable of supporting a throughput channel capacity of 65.5 Gbps. NG-PON2 network is designed and simulated at 187.1, 187.2, 187.3 and 187.5 to 187.8 THz wavelengths in downstream direction for different link distances from 40 to 80 km looking into the requirement of reach of access network for future cities. The network performance parameters such as bit error rate (BER), quality factor (Q-factor), signal-to-noise ratio using the Optisystem-16 simulator at above data rates and link distances. Further, channel capacity estimation is done for single-mode fiber channel coexistence NG-PON2 configuration up to 80 km supporting BER e-13 and Q-factor 7 for WDM link and BER e-12 and Q-factor 7 for a legacy network supporting almost-1 Gbps data rate to 65 users and 100 Mbps to 512 user.

Network survivability has become a crucial requirement in all types of computer networks. It becomes even more significant for wavelength division multiplex (WDM) mesh networks due to their high speed and capacity. These networks are prone to link failures. A link failure may be a single or multiple link failure. A single-link failure is easy to locate and fix as compared to multiple link failures. A dual-link failure recovery technique has been proposed using p-cycles. This technique uses a replication method for the p-cycle circle. It is an enhancement of the original failure independent path protection p-cycle scheme. The replica properties of p-cycle have been used to protect the nodes through the same p-cycle available. Creating a new p-cycle always adds to the cost of the network, whereas using a replica of already existing p-cycle significantly reduces the network cost. The proposed technique is implemented using network simulator in three phases.

In recent years the development of cloud computing, big data, cell phone application increases day by day and this will increase the work load on the server centers. Once the network traffic increases the power consumption also increases. In recent past, for reducing this power consumption arrayed waveguide grating (AWG) based optical packet switches are proposed. In these switches the physical and network layer analysis has been presented in isolated switch. In the core network to achieve low packet loss probability an effective buffering technique is required into the design of switch. In this paper a recirculating loop buffer based switch is presented, in this switch design for sharing the recirculating buffer, WDM technology is used by the packets. The main advantage of recirculating buffer is that it allows packet priority routing and by using this technique longer duration buffering of packet is achieved. This feature provides the quality of service in optical networks. In this paper, switch is deployed in the network and the performance of switch is measured when multiple switches are cascaded in the network simultaneously. The power analysis of switch is also performed for isolated and cascaded switches. For fixing the size of the switch into the network the concept of graph theory and random graph model is used.

The requirement for the huge bandwidth-demanding applications has urged researchers to develop improved data pipes that could allow smooth data flow. Revolutionary growth has been witnessed in the domain of the telecommunication industry, which has opened new horizons for connectivity among humans and devices alike especially, in the era of 5G. The advancement from TDM multiplexed signal transmitted over copper wire to the flexible and smart grid along with ethernet passive optical networks or space division multiplexed over optic fiber introducing enormous speed in 100 of Gbps has contributed to the fastest communication. The heterogeneous structure and network complexity require the automating of telecommunication services which have been assisted with the incorporation of machine learning and artificial intelligence, highlighting the new era of communication with the reliability and fastest accessibility. This survey reports the evolution of optical carrier generations and advancement in networks along with the fundamental achievements to comprehend the supportive competition while highlighting the gaps and challenges for future work.

Nowadays, the data centers have become a significant physical infrastructure for the purpose of supporting various Internet applications like cloud services, entertainment, web search and social networking. The traffic among the data centers is growing rapidly accompanied by the services that are obtained. The data centers are connected via fiber channels to support long-haul networks and high data rate transmissions by utilizing various modulation techniques. However, it has some drawbacks such as increased delay, computational complexities, high wavelength consumption, link failures, etc. Recently, researchers are focusing on improving the survivability and wavelength usage efficiency in optical data center networks. In this work, a novel framework depending on the concept of content connectivity is proposed for optical data center networks. Here, a mixed integer linear programming (MILP) is utilized for transmitting the data through optical data centers. The main intention of this research is to improve the performance and wavelength efficiency in optical data center networks. The performance of the MILP approach is evaluated and compared with the existing integer linear programming (ILP) technique and found that this new approach provides better performance with higher wavelength efficiency and reduced wavelength consumption.

Long reach Passive optical network (LR-PON) is an attractive solution to fulfill the ever-increasing bandwidth requirements due to propelling internet applications and competent to serve distant optical network units (ONUs). Wavelength division multiplexed (WDM) PON systems experience distance and performance limiting constraint termed as Dispersion. In order to compensate dispersion effects, Fiber bragg gratings (FBGs) and Dispersion compensation fibers (DCFs) are incorporated extensively in PONs. Performance of DCF is better than FBG in terms of dispersion compensation, but it comes at the cost of 3 $/m (very expensive). Therefore, long reach ultra dense WDM-PON systems are needed with incorporation of economical and high performance DCMs. Three newly constructed hybrid DCMs are investigated such as FBG-DCF (module 1), OPC-DCF (module 2), and FBG-DCF-OPC (module 3) in WDM-PON to get optimal DCM in terms of dispersion compensation efficiency (DCE) and economical operation. As per author’s best knowledge, DCE calculations and performance enhancement with cost reduction using hybrid DCMs in ultra dense WDM-PON, is not reported so far. WDM-PON consists of 32 channels at 25 GHz channel spacing is analyzed for 300 km link distance at 10 Gbps/channel using different hybrid DCMs. It is perceived that highest DCE of 70% is given by module 3 with maximum cost reduction of 19.84%. DCE performance of three modules is as follows: Module 3 (DCE 70%), Module 1 (DCE 55%), Module 2 (DCE 45%) and cost reduction/increase from conventional module by 19.84% reduction (Module 3), 19.05% reduction (Module 1), and increase 10.5% (Module 2). Hence, Module 3 is preferred for long reach WDM-PON to get high performance with lesser cost.

Signal remodulation mechanism is a promising cost-effective choice for future optical access networks. This paper investigates the scheme of the phase modulator to remodulate upstream data in the bidirectional WDM PON and TWDM PON system. The simulation results of downstream is carried out using two data formats such as RZ and NRZ at varying lengths of single mode fibers in this scheme. In addition, the upstream transmission compares different remodulators such as Phase modulator, Mach–Zehnder modulator (MZM) and Electroabsorption modulator. By analyzing the eye diagram and Q-value, the performance of upstream and downstream transmission is obtained. It is observed that the PM remodulation TWDM-PON with NRZ modulation format has better performance, which is a rational solution for NG-PON2 cost-effectiveness.

As the time progresses, the demand for bandwidth increases due to the evolution of new technologies supporting video on demand, music, etc., the traditional data centers heavily rely on electronics and thus dissipated a large amount of heat. To reduce both cabling and heat dissipated, fiber optic communication was supposed to be the next technology to replace current electronic systems, but unfortunately, fiber optic technology is not matured enough to be implemented. Therefore, as an alternative optical wireless communication (OWC) can be used, where advantages of optical components are availed and transmission media is free space, thus reducing cabling. This paper aims to present the modeling of wireless optical data center networks and evaluate bit error rate (BER) performance at the physical layer. To the best of our knowledge, this analysis is presented first time in case of OWC-based data centers.

As technology advancing day by day, the data rate of optical network is moving towards Tb/s speed. The minimum capacity utilization and survivability are the crucial requirement in such high speed optical networks. This research work presents a new approach to calculate both working and spare capacity with the help of single mathematical programming model named as joint capacity planning model. The working traffic and restored traffic are routed jointly in proposed joint capacity planning model. Therefore the joint capacity planning model required minimum capacity in as compare to other optimization models. To evaluate our model, three example networks are proposed i.e., network A (6 node), network B (8 node) & National science foundation network (14 node). Results of these networks are analyzed and compared. The capacity utilization is optimized by increasing the backup paths of the optical networks. It has also been proved in this manuscript that capacity requirement is dependent on the backup path. The proposed joint capacity model provides fast restoration speed and guaranteed protection for optical network.

The integration of the XGPON network with the 5G WLAN network is a suitable solution for next-generation high-speed access Internet service. We demonstrated the integration of two different standards via the QoS concept. Further, this work also presents a proper mapping scheme of QoS traffic between XG-PON and fifth-generation Wi-Fi standards known as IEEE 802.11ac. The analysis assessment compares the behavior of different IEEE 802.11ac standards with XGPON with-respect-to multimedia traffic in the FiWi network. To assess the performance of the FiWi network, the OMNET++ and INET framework are used to carrying out a comparative analysis in terms of upstream (US) delay and fairness index. The study concludes that the EDCA Wi-Fi module has better performance than the DCF Wi-Fi module with the integrated XGPON system for the FiWi access network.

Hybrid gigabit-passive optical network (GPON) is one of the hybrid optical networks, it integrates both Wave length Division Multiplexing (WDM) GPON and Time Division Multiplexing (TDM) GPON into a single passive network, which lowers the energy consumption, networking expenditure and boosts the data rate. In this paper, Radio over Fiber Technique of 10 GB/s GPON network architecture is implemented and verified using Quadrature Phase Shift Keying Modulation of 2.4 GHz radio frequency. Single-mode fiber of length 50 km is used to propagate the radio signals. Commercial OptiSystem simulation software is used to simulate the model. In total, 32 and 64 users are supported through this model. Based on the response of the constellation diagram, received power, eye diagram, and optical signal-to-noise ratio, the system is analyzed.

Large data centre provides the important facilities like storage, computation, communication, etc. Therefore, we must be very careful while designing the infrastructure and networking of the data centre as these factors decides the expenses on implementation and maintenance of the infrastructure. The data servers are connected with Top of Rack (ToR) switches, which are further connected to aggregated/core switches. This paper discusses the blocking performance of the switches used at various levels of optical data networks. However it must be noted that in data centres traffic is not blocked and but it is temporarily stored but if it can’t stored a negative acknowledgement is sent back and packet re-transmission is done. Blocking performance is done to judge the re-transmission of packets. Blocking performance is obtained using mathematical model as well as using Monte Carlo Simulations.

The characteristics of all optical networks such as high speed, data carrying capacity and transparency make them suitable for emerged networks domain. This paper presents an overview of research challenges in the field of all optical communication networks. Various subdomains of an all optical system, for example device-level designs, communication technique-level designs and network-level designs have been extensively investigated and presented in this paper. Further, the related research issues under each category of these domains have been discussed. These issues constitute the basic criterion for further development in all optical domain.

In this paper, we investigated N1-class Time and Wavelength Division Multiplexing (TWDM) Next-Generation Passive Optical Network-2 (NG-PON2) supporting symmetric and coexistence configuration in a worst-case scenario. The network is optimized in the presence of linear and nonlinear impairments such as chromatic dispersion (CD), self-phase modulation (SPM), cross-phase modulation (XPM), and four-wave mixing (FWM). On-off key (OOK) modulation technique incorporating hybrid optical distribution network (ODN) i.e., wavelength select (WS) and wavelength-routed (WR) ODN is used to connect downstream (D/S) and upstream (U/S) channels supporting symmetric 80 Gbps data rate operating at 2.5/2.5 and 10/10 Gbps, respectively. G.652 single-mode (SM) fiber channel is modeled for fiber launch power PT ODN  = 3 dBm and 4 dBm for D/S and U/S channels to implement N1-class network. The D/S and U/S receiver sensitivity (Rxs) demonstrated are −44.23/−37.46 dBm and −28.46/−35.32 dBm and inter-channel crosstalk (Cc) is −31.97/−31.39 dB accommodating 640 splitter configuration at 50 km in the presence of impairments at 10E-7 bit error rate (BER) and Quality (Q)-factor of 5 for 10 Gbps channel.

Ten Gigabit-capable ethernet passive optical network (GEPON) can quickly improve network bandwidth, meet multilevel business needs, and quickly improve the comprehensive competitiveness of the network. It is well known that the 10G EPON access network technology is used to carry IPTV services, VoIP services and high-speed Internet access, known as “triple play”, and IPTV services have been particularly popular in recent years. As the demand for IPTV service increases exponentially, a large amount of data will be generated, occupying a large access bandwidth and causing an impact on other services. Therefore, reasonable scheduling of IPTV service queue is an urgent problem to be solved under multiservice environment at present. Therefore, the design of PON bearing IPTV robustness algorithm to meet user experience is the focus of this paper. This paper proposes a Forward Error Correction with Weight Round Robin algorithm (FWRR), which adopts RS error correction code and Weighted Round Robin algorithm based on IP layer. When IPTV packet is lost at optical line terminal (OLT) end, downlink optical network unit (ONU) can recover the lost data through received packets. This mechanism can effectively solve the problem of packet loss caused by the blocking of OLT end, and realize the scheme of PON carrying IPTV multicast service. Simulations results in OPNET show that compared with weighted round robin (WRR) algorithm and round robin (RR) algorithm, FWRR mechanism can reduce packet loss, delay and jitter, in addition, improve the robustness of IPTV service in GEPON.

In this paper, the integration of the radio over fiber technology into a passive optical network (RoF-PON) is proposed to simultaneously distribute wired and two wireless standards each one transports 2 × 2 multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) signals. This simultaneous transmission is operated based on a single centralized optical wavelength and enabled by a polarization division multiplexing technique. The proposed RoF-PON system offers high spectral efficiency and is designed for unlicensed industrial, scientific, and medical bands at 2.4 and 5.8 GHz. The system performance is assessed by measuring the bit error rates (BERs) according to different access distances up to 30 km. After determining the optimum extinction ratio (ER) to modulate the baseband wired signal that allows jointly optical modulation of wireless signals using the same optical wavelength; all the 2 × 2 quadrature amplitude modulation (QAM) MIMO-OFDM wireless signals with a wired signal are successfully delivered without using forward error correction limit. Additionally, the system reliability has been confirmed by adopting other modulations schemes such as 8 and 16 phase-shift keying (PSK) that maintained good constellation diagrams performances. Whereas, the wired signal is analyzed according to its BER and quality Q-factor including high-quality eye diagram patterns. Also, the results revealed that the MIMO-OFDM signals mapped by 16 QAM scheme are given a better performance than PSK schemes when they are accompanied with high data rate baseband wired signal via a PON distance of 30 km.

Co-channel interference in the downlink of LiFi attocell networks significantly decreases the network performance in terms of rate. Analysis of multiple access schemes is essential to mitigate interference and improve rate. The light-emitting diodes (LEDs) being centrally monitored, the time division multiple access (TDMA) scheme over the LEDs will be suitable to analyze. This work considers the interference characterization in Ref. (Surampudi A, Ganti RK. Interference characterization in downlink Li-Fi optical attocell networks. J Lightwave Technol 2018;36:3211–28) over M-PAM modulated signals to derive an exact expression for the goodput G of the time scheduled attocell network, which is arranged as a deterministic square lattice in two dimensions. Given this TDMA over the LEDs, numerical simulations show that the LEDs can be optimally time scheduled to maximize the goodput, which implies that the TDMA mitigates interference in an attocell network compared to the case when the LEDs are unscheduled.

Light-Fidelity (Li-Fi) is the bidirectional communication technique, tenders almost unlimited bandwidth, exploit unlicensed spectrum of light waves. Accordingly, this manuscript illustrates usage of visible light communication (VLC) applied as Li-Fi, an efficient scheme to broadcast data wirelessly as well safer technique in contrary to the customary Wireless-Fidelity (Wi-Fi) networks. In support numerical simulations have been executed over the proposed Li-Fi model for the parametric variation with the data rate, laser power, modulation format and wavelength, communication length. Investigations have showed good output performance, with hike in data rate BER variation as 10 −94 –10 −23 and testing length. Simulations of network with DPSK and NRZ modulation formats at high data transmission of 10 Gbps have showed good output performance with 10 −40 with DPSK format. Li-Fi systems are quality solution for the impending communication systems save cost, provide high spectral efficiency.

Theory of chaos synchronization and quasi-period synchronization of an all optics local area network (O-LAN) is deeply studied and discussed, where two coupled-lasers are used as network’s double-star and the other single-lasers are used as network nodes. The LAN operates double-star lasers to drive node lasers in two links to perform a 2n−D (n is a positive integer, dimensions (D)) laser network. The O-LAN has the characteristics of an all optics LAN with double-center and two link nodes. Our theoretical and numerical results prove that the double-center lasers can obtain their synchronizations with each laser in two link nodes. A route to chaos after a quasi-period bifurcation is analyzed to illustrate dynamics distribution region of O-LAN. We find five quasi-period regions, four chaos regions, where there is a region where instability mixes with the first chaos, and a stable region. We find also that O-LAN can obtain its parallel multi-dynamics synchronizations, such as cycle-one synchronization, cycle-2 synchronization, cycle-3 synchronization, cycle-4 synchronization, cycle-5 synchronization, other quasi-period synchronization and chaos synchronization, shown in two links of O-LAN by shifting the currents of the lasers in one link. The theory of all optics LAN and its obtained results are useful to study on complex dynamic system, optics network, artificial intelligence, chaos and its synchronization.

A new architecture for increasing the number of simultaneous users in a hybrid system and providing a solution for the channel bottleneck problem has been designed and simulated. The 10G-TDM-OCDMA-PON system combines optical code division multiple access (OCDMA) and time-division multiplexed passive optical network (TDM-PON) techniques. The high bit rate TDM-PON system is based on a bit interleaving that uses noncontiguous order for data arranging manner, this system used to obtain ultra-high-speed data rate of 40 Gbps based on four TDM channels of 10 Gbps. The OCDMA system is based on two-dimensional single weight zero cross-correlation (2D-SWZCC) employing polarization and wavelength scheme with two orthogonal polarization angles (vertical and horizontal states). The proposed hybrid system increases the scalability by multiplexing M OCDMA codes in the same time slot of the TDM system that has N time slots. The results show that the proposed system with 2D-SWZCC has better performance with a high number of users and higher scalability than the system with 1D-SWZCC.

Gigabit-capable passive optical network (GPON) is a passive optical network that provides faster data transmission and reception using point-to-multipoint access technology with single fiber. Using passive splitter in distribution network to keep the costs down, its 2.5 Gbits/sec bandwidth can be split up to 64 times. This paper presents the study of max Q-factor, min bit error rate (BER) using Opti system 17. In this study return to zero (RZ) and nonreturn to zero (NRZ) line codes analyzed by using P-insulator-N (PIN) and avalanche photo diode (APD) receivers. This paper also studies the impact of CW laser power on Q factor and min BER of GPON with and without erbium-doped fiber amplifier (EDFA).

In this work, a 10 Gb/s–10 GHz hybrid orthogonal frequency division multiplexing (OFDM)-radio-over-free space optics (Ro-FSO) transmission link using 4-level quadrature amplitude modulation (QAM) has been modeled and its performance is investigated under different atmospheric conditions and system parameters. A link distance of 4000  m m at 10 Gb/s was achieved using the proposed link. Also, an improved performance by using a square root module (SRm) at the receiver end has been demonstrated. The results show a significant improvement in SNR and total received power using the proposed detection technique.

This work investigates the feasibility of terrestrial Optical wireless communication links under tropical and subtropical regions which are characterized by high precipitation. The impact of rain on propagating optical radiation is observed under controlled rainfall conditions using a laboratory testbed. Link degradation in terms of rain specific attenuation (RSA) is calculated experimentally and using known empirical models. A worst case analysis in terms of fade margin is carried out using measured and recorded data from Indian Meteorological Center to estimate the free space link feasibility for Indian tropical/subtropical climates.

This report examines the performance of a high-speed MDM transmission system supporting four nondegenerate spatial modes at 10 Gb/s. The analysis adopts the NRZ modulation format to evaluate the system performance in terms of a minimum power required (P N ) and the nonlinear threshold power (P TH ) at a BER of 10 −9 . The receiver sensitivity, optical signal-to-noise ratio, and the maximum transmission distance were investigated using the direct detection by employing a multimode erbium-doped amplifier (MM-EDFA). It was found that by properly optimizing the MM-EDFA, the system performance can significantly be improved.

With the rapid growth in the internet applications, pressure is observed on the optical communication systems. Free space optical communication (FSO) is very important alternative to the optical fiber because of elimination of licenses, trenching, and no cost of ways and saves the time of installation. Wavelength division is capacity enhancement multiplexing but due to large number of laser requirements, it becomes expensive. Mode division multiplexing (MDM) is suitable multiplexing technique because it needs only single laser and can support high data rates. Optical code division multiplexing and MDM is demonstrated in this work at 100 Gbps over FSO supporting 10 users. Multiple access interference is prominent issue in OCDMA codes and in order to suppress MAI, zero cross correlation codes are used and use of Laguerre Gaussian modes has been done. Different fog conditions are analyzed and two different OCDMA cods are incorporated as well as compared in the proposed system such as shift zero cross correlation codes and multi diagonal codes in terms of Q factor and BER.

Orthogonal frequency-division multiplexing technique (OFDM) has been adopted widely as a modulation technique for radio frequency (RF) and optical communication systems such as visible-light communication (VLC) due to its high spectral efficiency and low-complexity implementation. VLC-OFDM is recommended in 5 G mobile communication. However, VLC-OFDM suffer from the high peak to-average power ratio (PAPR). In this paper, a modified selective mapping (MSLM) method is applied to the proposed system followed by a new envelope scaling process for further reductions in PAPR of VLC-OFDM system. Simulation results show that the proposed method reduces the PAPR by about 6.8 and 1.7 dB comparing with the original signal and the traditional SLM with a number of rotation vector U = 8, respectively.

Radio over free space optics (Ro-FSO) innovation saddles the vast limit of optical fiber and the portability from local to remote systems. To enhance the capacity of Ro-FSO systems without compromising the bandwidth, this work incorporates use of hybrid polarization division multiplexing (PDM) with optical code division multiplexing (OCDMA) schemes. Due to low deployment time and support cost, the vast majority of the current optical network application systems adopts free space optics (FSO) as the elective answer for suitably supplanting fiber optical cable. This study has incorporated PDM and OCDMA schemes to design a 50 Gbps Ro-FSO link. Ten channels, each with 5 Gbps of data, are transported via FSO link of 3500 m. In addition, the proposed PDM-OCDMA-Ro-FSO link is evaluated under various atmospheric commotions.

Satellite-to-Ground Downlink-Free Space Optics (SatGD-FSO) communication systems are emerging as the key driver for telecom investment, with several factors driving this convergence. It is attractive to minimize the size, weight, and power profiles of the space terminals by utilizing high affectability and huge accumulation collection zone ground terminals. Multiaperture coherent receivers using spatial diversity approached is considered on the attractive solution can fulfill this necessity and have numerous focal points over the single enormous opening cognizant recipients. The effects of atmospheric and climatic conditions using various dynamic system parameters have been investigated as a function of bit-error-rate (BER) performance of multiaperture coherent receivers. Types of orbits, aperture averaging, zenith angle, transmit optical power, and modulation schemes are systematically investigated and compared to the SatGD communication system. The proposed solution with a maximum throughput of 2.5 Gbps is useful for a plan and optimization improvement of the SatGD-FSO systems.

The evolving 5G technology is currently facing some huge challenges such as cost, bandwidth, network flexibility, deployment and capacity. Free space optics (FSO) is an emerging technology and viable approach to address the challenges of upcoming networks. This paper presents the performance comparison of advance variants of Return to zero (RZ) and Non-return to zero (NRZ) modulation formats in FSO communication. Detailed analysis of FSO link is carried out under various weather conditions by means of numerical simulations in which different data rates and distances are tested to evaluate the performance. The effects of different weather conditions over the performance, efficiency and availability of FSO link are analyzed on the basis of quality factor (Q-factor) of received signal. The work is performed on the licensed version of Optisystem v14.0.

Free Space Optics (FSO) communication provides attractive bandwidth enhancement with unlicensed bands worldwide spectrum. However, the link capacity and availability are the major concern in the different atmospheric conditions. The reliability of the link is highly dependent on weather conditions that attenuate the signal strength. Hence, this study focuses to mitigate the weather and geographic effects using iterative optimization on FSO communication. The optimization maximizes the visibility distance while guaranteeing the reliability by minimizing the Bit Error Rate (BER). The wireless optical communication system is designed for the data rate of 10 Gbps. The performance of the proposed wireless optical communication is compared against the literature in terms of visibility distance, quality factor, BER, and Eye diagram at different atmospheric conditions. The simulation results have shown that the proposed work has achieved better performance.

In free space optics (FSO) optics, the tweaked optical sign is transmitted at different climate conditions like day off, Mist, and Haze, which is a new paragon to the field of optical communication. Further to realize the same, the present research analyzes the framework performance by executing two adjustment strategies amplitude shift keying (ASK) and Phase shift keying (PSK). Moreover, article investigates the performance of applied modulation-based free space optic system using a coupler-based delay line filter. Aside this, the recreation results are examined and natter about the dependent of quality factor, bit error rate (BER), and eye outline of various FSO parameters pertaining to the same. The outcomes of the research bestow on the recreation results acquired for quality factor and BER against various conditions with respect to the both adjustment techniques and PSK offers better execution.

Optical communication systems represent the backbone of modern long-haul communication networks. Nonlinear impairments such as the Kerr effect pose threat and deteriorate transmission in long-haul optical communication systems. At high launch powers, nonlinear effects become more important and their compensation is entailed to improve the transmission performance. In this paper, one of the major nonlinear effects of four waves mixing (FWM) is addressed using a theoretical model and validated through simulation in Optisystem. Two mechanisms with and without dispersion variation are investigated. The impact of FWM is investigated in terms of various values of launch power. The transmission performances of the proposed model are evaluated on the basis of bit error rate, optical signal to noise ratio, and quality factor using key parameters of effective area, nonlinear refractive index, nonlinear dispersion, and linear dispersion.

Free space optics is a light-wave communication technology that operates in the near-infrared region of the electromagnetic spectrum (about 700–1675 nm) and uses atmospheric channel as the transmission medium for both inter-satellite and terrestrial networks. However, the operational proficiency of free space optical communication system is highly affected by channel dynamics which cause signal attenuation that results in short link range. To master these shortcomings different methods have been suggested in the literature, from transceiver design and diverse channel models to adaptive algorithms. In this manuscript, the design and performance investigation of free space optical system has been carried out for three optical transmission windows; 850, 1310 and 1550 nm by means of on-off keying digital modulation technique. The system analysis has been done taking bit error rate, quality factor and received optical power as the performance metrics. Their variation pattern with respect to varying link parameters such as range, transmitted optical power and beam divergence has been investigated. In addition, the observations made are well validated with thorough mathematical justification.

Here, we have simulated different unidirectional passive optical networks (PONs) technologies such as wavelength division multiplexing (WDM), time-division multiplexing (TDM) and hybridPONs with different users for varying fiber length, data rate, continuous wave laser power and number of users. Their performances based on the quality-factor (Q-factor) and bit error rate (BER) using OptiSystem software 7.0 with using an Erbium doped-fiber amplifier (EDFA) were compared. Our model used 16 and 128 users, where the performance of the unidirectional Hybrid WDM/TDM PONs with 4 wavelengths and 128 user systems have better high Q-factor and lower BER, compared to that of 128 user WDM PON and 128 user TDM PON systems.

Free-space optics (FSO) connects two distant points by a simple light beam. Currently, this technique is a complement to radio frequency systems and those based on optical fibers. However, its large-scale deployment is slowing down due to major drawbacks such as the short operating distance and its great vulnerability to atmospheric conditions. In this article, and in order to increase the connection distance of the FSO systems and maintaining an acceptable signal quality, we inserted in the transmission channel: a receiver and a transmitter that retransmit the received signal. We have chosen two weather situations. The attenuation values used are 85 dB/km and 170 dB/km. They represent two different fog densities. For an attenuation of 85 dB/km, the quality factor Q degrades and goes from the value 44.50 to 2.60 when the distance goes from 90 to 180 m. With the proposed technique, the quality factor has improved significantly since we obtained a value that is equal to 29.82 instead of 2.60 at the overall distance of 180 m. On the other hand, we increased the distance until we obtained a quality factor around 2.5. The distance obtained is equal to 360 m, which is twice the initial distance.

Nonlinearity, flat gain and noise figure are the prime concern for super dense wavelength division multiplexing (SD-WDM) systems which have been resolved from RAMAN-RSOA hybrid optical amplifier (HOA) for the first time in this paper. Channel capacity is taken up to 400 with data rate of 10 Gbps. Performances are evaluated with respect to C + L + U band for 1520–1680 nm and 1520 to 1640 nm. RSOA is operated at 40–120 mA bias current to attain best rating flat gain of 34.07 dB with variation of 3.5 dB than the others HOAs (RAMAN-EDFA, RAMAN-SOA and EDFA-SOA). Moreover, the impact of EDFA-SOA is not acceptable in terms of noise figure for SD-WDM optical communication system.

This paper presents for non-coherent Optical Code Division Multiple Access (OCDMA) systems a new optical code namely Two-Dimensional Half Spectral/Spatial Zero Cross Correlation (2D-HSSZCC) code based on a One-Dimensional Zero Cross Correlation (1D-ZCC) code already developed using block matrices characterized by a high capacity. The results of simulation show that the use of the new (2D-HSSZCC) code eliminates totally the Multiple Access Interferences (MAI) due to the zero cross correlation flexibility, and less complexity of the code construction which produces a very low bit error rate of closely (4×10 −18 ) at 1 Gbps for four users with a low power source of −12.60 dBm to reach a high data rate and high number of simultaneous users upper to closely 149, save an effective power around −1.35 dBm, −3.3d Bm compared between those provides by (Two-Dimensional dynamic cyclic shift (2D-DCS) code and Two-Dimensional Dimensional Diluted Perfect Difference (2D-DPD) and (1D-ZCC) code, and increase the cardinality percentage upper to 1.58, 2.19, 2.33 and 3.9 times comparing to (2D-DCS) code, 2D-DPD code, 1D-ZCC code and Two-Dimensional Flexible Cross Corelation/Modified Double Weight (2D-FCC/MDW) code. On the other hand, 2D-HSSZCC code is comparied with other codes which has it same property namely Two-Dimensional zero cross correlation/multi diagonal (2D-ZCC/MD) and (2D-MD) codes where the increased percentage in system capacity was 1.38 and 1.05 times, respectively. Finally, the results obtained in part 1 (with Matlab software) were confirmed and validated with the Optisystem software, the proposed system gave a better BER minimum value around 10 −21 and a maximum value of the Q factor of around 9.4 at 622 Mbps of data rate when the number of simultaneous users increases.

This work clarifies the analysis of the theoretical study of noise and transmission gain characteristics of semiconductor optical amplifiers (SOAs), which are relevant in the novel local area optical communication systems. We investigated the effects of noise on AlGaAs/GaAs SOA transmission performance through the measurement of output power, optical gain, the optical signal-to-noise ratio, and noise figure. It was observed that noise has a dramatic effect on SOAs’ operation transmission efficiency, and the performance of the amplifier structure may be limited. If the drive current and injection power at the SOA can be changed and its active region length modified, then the variation of gain, optical signal-to-noise ratio, and noise figure at the output of the structure can be obtained.

In this work, the integration of free-space optics (FSO) technology for implementing long-haul high-altitude platform (HAP)-to-ground transmission system is proposed. Mode division multiplexing (MDM) and orthogonal frequency division multiplexing (OFDM) are incorporated for carrying high-speed signals without interference. The impact of increasing input power, divergence angle, antenna diameter, and attenuation on the system performance is further investigated. In addition, the performance of the MDM-OFDM-HAP-to-ground FSO transmission system is improved by using a square root module at the receiver for link reach enhancement. The results exhibit a reliable transportation of 40 Gbps information over 20 km FSO distance with good quality of the received signal.

Radio over Fiber (RoF) is a technology that inherits both from optical and wireless technologies in order to send radio frequency signals over a fiber architecture. RoF technologies are mainly utilized in the front-haul link of telecommunications architecture, where the base stations communicate with the central station. This is conventionally done either through microwave signals or copper cables. In this paper, we have designed and evaluated a full-duplex link between four base stations and a central station. The error performance of the system is evaluated in terms of eye-diagrams and Q-factor using Optisystem. The system is found to perform reasonably well up to a link length of 90 km for 5 Gbps data transmission with a Q factor of 30.8.

In the present study, the application of free space optics (FSO) transmission system to realize a long-reach high-altitude platform (HAP)-to-satellite communication link has been exploited. High-speed information transmission without interference is accomplished using orthogonal frequency division multiplexing (OFDM). Further, the information capacity of the proposed system is increased by employing mode division multiplexing (MDM). We have investigated the proposed MDM-OFDM-HAP-to-satellite FSO transmission system performance over varying FSO range, diameter of the receiver, pointing errors, and input power. Also, an improved transmission performance of the proposed system using a square root module is reported.

This paper presents the high capacity single-tone Radio over Fiber (RoF) system utilizing advanced modulation technique in conjunction with optimized dispersion compensation scheme to support the high data rate transmission upto 120 Gbps. The proposed system incorporates the Integrated-Alternate Mark Inversion (I-AMI) modulation and Symmetrical-Symmetrical-Post (SSP) compensation technique to enhance the spectral efficiency as well as to reduce the chromatic dispersion effects in long-haul RoF link. The proposed system i.e., I-AMI with SSP has been examined at 60, 80, 100 and 120 Gbps bit rate for various transmission distance. The simulation results obtained in terms of Q-factor, Bit Error Rate (BER) and eye diagram reveal that the proposed system provides wider eye-opening, low BER and high Q-factor as compared to the existing system. The proposed I-AMI with SSP provides the Q-factor of 30.47 whereas the I-AMI with PSP and AMI with SSP provides the Q-factor of 18.77 and 18.40 respectively at 80 Gbps bit rate over a transmission distance of 800 km.

Filter bank multicarrier (FBMC) is a new waveform candidate in the visible light communication system (VLC). FBMC is a particular sort of multi-carrier modulation that can be viewed as an option in contrast to orthogonal frequency division multicarrier (OFDM) with CP (cyclic prefix). The point is to defeat some innate disadvantages of the normally utilized optical OFDM schemes. The principles of key transceiver should be intended to suit the necessities of the channel of IM/DD. Peak to average power ratio (PAPR) and bit error rate (BER) performance of FBMC based VLC are discussed and compared with scheme of optical OFDM. FBMC based VLC system with clipping technique has the lowest PAPR and good BER performance compared to conventional system in this paper. This paper recommends that FBMC based VLC has an incredible potential for optical wireless communication systems with high-speed. Matlab program simulations confirm the analysis. The results may shed light into potential research line on FBMC based VLC systems.

In order to improve the performance of the Spectral Amplitude Coding-Optical Code Division Multiple Access (SAC-OCDMA) system, a zero cross-correlation (ZCC) code named double weight multi-diagonal (DW-MD) is proposed with constant weight (CW) or variable weight (VW). Mathematical results illustrate that it is feasible to reduce the number of filters without sacrificing system performance by using the CW DW-MD code instead of the multi-diagonal (MD) code. And for the VW DW-MD code, the supportable number of users for lower code weight W L (3) at bit error rate (BER) of 10 −3 (voice) is 43, medium code weight W M (4) at BER of 10 −9 (data) is 29, and higher code weight W H (5) at BER of 10 −12 (video) is 32. Finally, the analysis about the position of chips “1” is given, and the simulation setups show that the CW DW-MD code outperforms the MD code when Gaussian optical filter is used.

Free space optical (FSO) communication refers to a line of sight technology, which comprises optical source and detector to create a link without the use of physical connections. Similar to other wireless communication links, these are severely affected by losses that emerged due to atmospheric turbulence and lead to deteriorated intensity of the optical signal at the receiver. This impairment can be compensated easily by enhancing the transmitter power. However, increasing the transmitter power has some limitations as per radiation regulations. The requirement of high transmit power can be reduced by employing diversity methods. This paper presents, a wavelength-based diversity method with equal gain combining receiver, an effective technique to provide matching performance to single input single output at a comparatively low transmit power.

In this paper, the performance of two-dimensional (2-D) wavelength-hopping/time-spreading (WH/TS) optical code division multiple access (OCDMA) system over free space optical (FSO) channel is analyzed in the presence of pointing error and different weather conditions. Prime code scheme is employed for both wavelength-hopping and time-spreading to address user code-matrix. The operating central wavelength of 1550 nm is considered to demonstrate the bit error rate (BER) performance of the proposed system as a function of various system parameters. The required optical power of the proposed system is determined to maintain a BER value of 10 −9 . The numerical evaluation interprets that the BER performance is highly dependent on transmission length, transmitted power, pointing error angle as well as the number of simultaneous user. It is also observed that the 2-D OCDMA system over free space needs minimum required optical power in case of rainy atmospheric condition, but it is maximum for foggy atmospheric condition.

Underwater wireless optical communications (UWOC) recently emerge as a solution to the problem of underwater communication for link with a high data rate, low delay, safety, and high immunity. In this study, the line of sight (LoS) method based on LED used for UWOC with different modulation schemes. The bit error rate (BER), signal-to-noise rate, and quality factor are used for assessing system performance and link quality. Besides the effect of transmitting angle, distance link ( d ), and transmitting power ( P T ) are analysed. Results show that 8-pulse position modulation (PPM) is the best modulation scheme for achieving a good link in the LoS method.

In this paper, a system was designed to simulate the study and analyze the effect of chlorophyll on the underwater wireless optical communication system. Chlorophyll was extracted and characterized by measuring absorption and fluorescence spectra, the performance of system was observed by mixing various volumes added to water. The optical beam was modulated at different frequencies by the frequency shift key, once through clean water and once through water mixed with chlorophyll and different metrics such as received power ( P r ), attenuation coefficient ( α ), peak-to-peak voltage ( V p-p ), voltage gain ( A v ), and signal-to-noise ratio were measured to assess the performance of the system. The results refer that the system exhibits a good link quality to the received frequencies under different conditions.

A subcarrier multiplexed radio over fiber (RoF) system using optical single sideband (OSSB) modulation is proposed. OSSB modulation reduces the bandwidth requirements and also combats the radio frequency (RF) power fading issue due to the dispersive effects in optical fiber. Subcarrier multiplexing (SCM) is a technique used to transmit multiple RF signals through the same optical fiber to utilize its large bandwidth. A theoretical analysis showed that OSSB generation with a number of subcarriers can be done by Hilbert transform method employing a single dual drive Mach–Zehnder Modulator (MZM). This technique is very relevant in the emerging 5G standards which require accesses of multiple standards simultaneously (5G, LTE, and Wi-Fi). This paper demonstrates a low cost solution of OSSB-RoF system and more effective utilization of the spectrum. Simulations results showing satisfactory reception of signals up to 50 km.

Free space optics (FSO) is a novel transmission technique capable of providing high-capacity links with large bandwidth and robustness against electromagnetic waves interference. In this work, we demonstrate the development of a 100 Gbps FSO link which employs the hybridization of polarization division multiplexing technique and coherent detection-orthogonal frequency division multiplexing technique. Further, we have investigated the system performance by varying different parameters like the input power, the size of the receiver antenna, wavelength of laser beam, the angle of beam divergence, and the additional losses. The proposed system has been modeled and analyzed over Optisystem test bed.

Fog attenuation causes more loss than other weather conditions in a free space optics (FSO) link thus limiting the visibility distance. This work presents a detailed survey on the attenuation of the transmitted signal as a result of variation in visibility range caused by different fog conditions of the Delhi, Safdarjung region. Kim and Kruse models have been used to calculate attenuation as a result of fog conditions for three specific months (January, February and December) for seven consecutive years starting from 2013 to 2019. Received signal quality has been analyzed as a function of transmitted power, data rate, transmission range and operation wavelength. Descriptive statistical analysis of real time observed visibility data allows for the estimation of specific optical attenuation and enables in determining the link availability of the region for the complete year.

A energy efficient and high throughput bi directional radio over fiber (RoF) system is designed and analysed. In order to preserve the phase and the magnitude of the transmitted signals, coherent detection (CD) is employed and hence an optical local oscillator (OLO) source is used. A full duplex system is designed by utilising the same OLO. The phase noise in CD system is logically cancelled using digital signal processing techniques. 10 Gb/s 16-QAM at 5.5 GHz, 10 Gb/s 2-QAM at 2.5 GHz , 5 Gb/s QPSK at 5.5 Ghz and 10 Gb/s 4-QAM at 7.5 GHz are transmitted simultaneously over 25 km optical fiber(OF). It is analysed that any coherent RoF system can be designed to a full duplex system with acceptable log(BER) and error vector magnitude(EVM) values. The minimum values of log(BER) values obtained for 16-QAM, QPSK, 2-QAM and 4-QAM are −10, −8, −16 and −22, respectively.