Volume 42, Issue 2

In this paper we have study the performance of different optical amplifiers (Erbium doped amplifier (EDFA), RAMAN amplifier, and semiconductor optical amplifier (SOA)) for 80 channels wavelength division multiplexing (WDM) system with the data rate at 10 Gbps data rate for the transmission distance of 280 km After getting the results of these amplifiers the performance of these has to be compared The Q-factor values achieved better in EDFA as compared to SOA and RAMAN. While the BER getting good in SOA as compared with other amplifiers but in EDFA after 200 km it goes saturated, the Power achieved at the power estimator is getting better in EDFA optical amplifier while in other amplifier it achieved negative. At the end it is also study the Power with frequency in THz and the Eye Diagram of such amplifiers results.

The aim of this paper is to analyze the performance of RAMAN amplifier (RAMAN), Erbium-doped fiber amplifiers (EDFA) and semiconductor optical amplifier (SOA) amplifiers separately at 10 Gbps data rate for 32-channel WDM system for a fiber length of 40 km to 280 km. Depending upon the results, the performance of the three amplifiers has been compared. It is observed that RAMAN amplifier provides a better result in terms of Q factor up to a fiber distance of approximately 20 km and in terms of bit error rate (BER) up to a distance of approximately 40 km among all the three amplifiers. EDFA starts providing better Q factor after a fiber distance of approximately 20 km and better BER after a fiber distance of approximately 40 km among all the three amplifiers. But power received is minimum in case of RAMAN amplifier. In terms of power received, SOA provides better result up to a fiber distance of approximately 120 km and after that EDFA provides a better result in terms of power received among all the three amplifiers. All these parameters ( Q factor, BER and power received) are also analyzed for different values of laser power. Finally, the eye diagram has also been analyzed.

In this paper we will propose and design an all optical phase shift keying (PSK) demodulator using photonic crystal based coupled waveguides. The proposed structure should be designed such that it can generate digital 0 and 1 based on the phase of the input signal. The working mechanism is based on constructive and destructive of optical beams. The proposed structure was simulated using plane wave expansion and finite difference time domain methods. The simulation results show that the rise and fall times for the proposed structure are about 1.2 ps and 0.2 ps, respectively.

Recently, an explosive growth has been observed in data traffic, which restricts the speed of exiting data communication network. To solve such problem, fiber optical-based optical communication is preferred choice. In this paper, a switch design is proposed to tackle contention problem in Optical Packet Switching (OPS) and data center networks. The proposed switch is compared with recently proposed switch design and advantages of proposed design are presented. To show superiority of the proposed design over earlier one, mathematical modeling is presented and expressions for noise figures and Bit Error Rate (BER) are derived. Using the mathematical framework, switch analysis is done in terms of BER and packet loss probability, and it has been found that power required for correct operation of the switch is lesser in comparison to earlier one. The effect of recirculation count on packet loss probability is detailed. The network layer analysis in terms of packet loss probability is also done using Monte Carlo simulation, and relation between physical and network layer parameters is also discussed.

All optical logic gates can play very important roles in all optical digital systems. In this paper we designed an all optical XNOR gate. The switching part of the designed XNOR consists of two nonlinear resonant cavities. The nonlinear cavities were created by adding two nonlinear defects made of doped glass. Plane wave expansion and finite difference time domain methods were used for simulating the designed structure. The final structure has two input and one output ports. The output port is ON when the input ports have similar states. For the designed structure the delay time is about 2.5 ps.

The current study investigated saturable absorption of a single-wall carbon nanotube (SWNT) layer in the optical spectral range. Initially, a glass substrate was covered with an SWNT layer several μm in width to determine its attenuation properties in the optical telecom spectrum. The spectral response of the broadband source (BBS) was 1260 to 1640 nm, linear and non-gradient. Attenuation behavior in the narrow spectrum sources depended on optical power variation. Saturation absorption occurred at the peak of optical power. This characteristic was observed for laser diodes with wavelengths of 1310 and 1550 nm. The EDFA optical amplifier showed saturable absorption. This property can be applied to increase side mode suppression ratio 7 dB in laser diodes and improve optical signal-to-noise ratio (OSNR) 8 dB in optical amplifiers.

Free-Space optical (FSO) link is an optical communication technology that uses light or laser as the carrier diffuses into free space to transfer data information between the transmitter and the receiver through the air channel. In this paper, a dual transmitters and receivers with multi-beam technique were designed to Study the effects of rain attenuation on the system to be used through FSO during the rainy weather. FSO model system was designed and simulated using OptiSystem7.0 software. The results analysis of FSO link within (1.6 - 3.9 km) ranges according to a Charbonneau model for rain attenuation. The transmitting data with NRZ modulation was designed and analysis of the performance System efficiency parameters such as bit error rate (BER) and Q. Factor for different optical links. The results of the simulation showed that the received signal power decreases and the bit error rate is increasing when the rain rate is increasing.

Failures and malicious attacks in high-speed optical networks lead to huge data as well as revenue loss. In this paper, a survivability technique called Dynamic and Hybrid with Multiple Backup selection Criteria technique for high-speed networks has been proposed with the objective to minimize network resource utilization, blocking probability, End-to-End delay and maximize throughput. The proposed model decides the type of backup provisioning technique based on the location of failure in the network. Protection has been provisioned to selective links near to destination node and other links are restored. The simulation results indicate that proposed survivability technique is efficient as compared to conventional techniques in terms of various network performance measuring parameters. This technique inherits merits of protection as well as restoration. It can be practically implemented to provide resilience in future high-speed networks.

In this paper, an algorithm for multipath connection provisioning in elastic optical network (EON) has been proposed. Initially, the algorithm prefers the single-path routing for service provisioning. But when single-path routing is not adequate to serve a dynamic connection, the algorithm switches to the connection request fragmentation. Its computation is based on the parameters such as capacity_constant and capacity_allowed to fragment the connection request on disjoint paths. Simulation results clearly state that the proposed algorithm performs well in service provisioning as compared to the traditional single-path routing algorithms and improves the average network throughput. Thereafter, we have investigated the limitation of Erlang B traffic model in EON for calculation of link blocking probability using routing and spectrum assignment (RSA) algorithm. It is verified by the following two ways: (i) effect on the blocking probability in case of constant load and (ii) effect of slot width on the blocking probability. Our simulation results indicate that in EON due to dynamic RSA, blocking probability is not constant in case of proportionate varying of call arrival and service rate giving constant load and blocking probability depends on the number of slots per link, but in Erlang B traffic model blocking probability is always constant in case of constant load and it considers wavelength per link instead of slots per link. This is attributed to the fact that Erlang B traffic model fails to calculate blocking probability accurately in EON. We have computed the carried traffic on 14 nodes, 21-link National Science Foundation Network (NSFNET) topology.

In this paper, link fault tolerant algorithms (LFTAs) are employed for optimization of blocking performance in optical burst switching (OBS) networks for dynamic establishment of wavelength-routed lightpaths. This paper presents two algorithms: link fault tolerance algorithm for least congestion (LFTALC) and link fault tolerance algorithm for optimized blocking (LFTAOB). In former algorithm, the path with least congestion is selected and in the latter algorithm the path with least blocking probability is selected and then both the algorithms check for the availability of fault on the links present in the selected path. The findings indicate that methods of developing link based fault tolerant algorithms keep good performance and fairness among all the connections. The key advantage of these proposed algorithms as compared to routing and wavelength assignment algorithm is that these are very simple in nature and require less service disruption time.

Survivable virtual optical network (VON) mapping is researched to overcome the ossification of current network architectures. In this paper, we study the survivable VON mapping problem in elastic optical network (EON) with the objective of minimizing the average resource consumption of VON request. We propose a protective algorithm, namely, coordinated mapping algorithm based on minimum spanning tree (CMST), to provide the dedicated protection against the single physical link failure. In CMST, for virtual node mapping, we not only consider the resources constraint but also the node degree constraint. For virtual link mapping, we adopt the coordinated mapping method for part of the virtual nodes and virtual links. And we provide the backup path for the minimum spanning tree link of virtual topology to reduce the resource consumption. Simulation results showed that CMST can reduce the VON request blocking probability and average network resource consumption. And it can increase the revenue of physical network.

Radio over fiber (RoF) technique has revolutionized communication industry with its high data transmission rate and ability to carry the radio signal with speed of light. It finds its application in wireless local area networks (WLANs) due to easy of deployment and low cost. This paper utilizes alternate mark inversion (AMI) technique in wave length division multiplexing (WDM) scheme to further enhance data carrying capacity of the system. It is observed that proposed AMI-WDM scheme is better technique for providing high data rates and is confirmed via SNR, Q factor and eye diagrams.

Providing reliable connection-oriented services in wavelength division multiplexing (WDM) networks becomes challenging because of bad channel quality and overload. Most of the existing works have not considered node failures and congestion which are the essential characteristics for survivable routing. In this paper, a load and link aware protection switching technique for survivable routing in WDM networks is proposed. The technique estimates k -shortest paths for a connection request. Based on four different path possibilities, it provides the best path as connection path in terms of bandwidth. For establishing the primary path, the least virtual hop first routing algorithm is used. If the source node receives either failure or congestion warning message from the intermediate nodes, it triggers the load balanced rerouting algorithm for establishing the backup path. The proposed technique is simulated in NS-2, and the simulation results prove the efficiency of the scheme.

High-capacity and long-haul transmission gained great significance in modern communication networks. Optical fiber communication system is good enough to face the high demand of current telecom terrific. This paper will propound the theoretical model showing nonlinear factors which degrade the transmission performances of high-capacity long-haul network. The postulatory model will be validated using simulation of key nonlinear factors such as effective area, launch power, refractive index and fiber length. The transmission performance of the high-capacity long-haul optical network would be analyzed on the basis of some key parameters such as bit error rate and signal-to-noise ratio. Mitigation of nonlinear impairments shows significant impact on transmission performances of high-capacity long-haul optical networks.

Existing single-channel orthogonal frequency division multiplexing (OFDM) system can transmit data from single source to single destination occupying the entire link but bit error rate (BER) provided by these systems is quite high. The multichannel system gives the liberty to route the traffic through the different channels depending upon the availability. So there is a need to design a multichannel system which can transmit the data at higher rate by transmitting multiple symbols simultaneously with improved BER. So, in this research work, we propose a multichannel OFDM system by using an advanced modulation technique, i. e. quadrature amplitude modulation which not only improves the capacity but also makes the system power efficient. In order to demonstrate that our proposed system is power efficient, a set of simulations have been performed. Results show that BER (as a function of power) obtained for the proposed system is low in comparison to the already existed phase shifting keying- and differential phase shift keying-based system.

In this research study, different Peak Average Power Ratio (PAPR) based reduction techniques, namely, A-Law companding, µ-Law companding, Clipping & Filtering and Clipping are analyzed for Filter Band Multi-Carrier (FBMC) with different transmission systems such as Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), 64-QPSK and 64-Quadrature Amplitude Modulation. It is estimated that the PAPR reduction can benefit by using clipping technique in FBMC.

The 5 G technology provides a promising solution for future broadband networks. It requires access to high-speed wireless services for systems at anytime and anywhere. For adapting the 5 G services, this paper proposes an optical wireless system with hybrid scheme of dual polarized Gbps dense wavelength division multiplexed (DWDM) system. The multi-carrier transmission technique such as coherent optical orthogonal frequency division multiplexing (CO-OFDM) has also been incorporated into the system. The frequency spacing for the DWDM system is taken 25, 50 and 100 GHz according to the ITU-T standard. Here the subcarriers of each channel are modulated with the dual polarized-quadrature phase shift keying (DP-QPSK) sequence. The information is transmitted with an overall data rate of 0.32 Tbps. The system is successfully demonstrated at different turbulence regime from clear weather to severe turbulence weather under Gamma-Gamma atmospheric turbulence channel model. Due to the high optical signal-to-noise ratio (OSNR) tolerance and high spectrum efficiency of the dual polarized multi-channel and multicarrier transmission technique, the link distance achieved is 2.9 km in clear weather, 2.6 km in moderate turbulence regime, 2.3 km in high turbulence regime and 0.9 km in severe turbulence regime. A comparison study with related works has been carried out. Mathematical modeling is also incorporated for detail analysis of the proposed system.

This paper presents a new form of orthogonal frequency division multiplexing (OFDM) termed as hybrid noise cancelled asymmetrically clipped optical OFDM (HNC-OFDM) for optical wireless communication. This HNC-OFDM is formed by combining the concepts of noise cancelled asymmetrically clipped optical OFDM and DC biased optical OFDM (DCO-OFDM). HNC-OFDM has the same bit error rate (BER) performance and dimming flexibility but less complexity compared to the recently developed hybrid diversity combined OFDM . The optimum DC bias level for HNC-OFDM, DCO-OFDM and asymmetrically clipped DC biased optical OFDM is shown to depend on the target BER, the constellation size, the received signal to noise power ratio, the proportion of DCO-OFDM element, the link type, equalization, etc. Simulations results show that with an optimum bias, HNC-OFDM can outperform others in an average power limited channel, while DCO-OFDM is a better choice for a peak power limited channel.

The main drawback in the performance of the Orthogonal Frequency Division Multiplexing (OFDM) system is the higher Peak-to-Average Power Ratio (PAPR) of the OFDM signals at the transmitter side. Companding is a well-known technique useful for reducing PAPR in the OFDM signal. This paper proposes a new nonlinear companding scheme that transforms the magnitude of Rayleigh distributed OFDM signal of specific degree into trapezoidal distribution. Additional design parameter is used in the proposed companding scheme to make the companding function more flexible. In the designed OFDM system the companding function has more degree of freedom which improves the PAPR and bit error rate (BER) parameters of the designed system. It has been demonstrated that the designed companding scheme provides more flexibility to accomplish an optimum trade-off between the performance parameters PAPR and BER of the designed OFDM system.

In order to achieve large capacity inter-satellite communication, optical wireless communication (OWC) is emerging as a promising area of research amongst the academic and research groups. While radio over fiber (ROF) and advanced modulation technique is considered to be a key enabling technology in the development of OWC based access networks for high-speed data transmission. This paper has proposed a novel ROF based system model using OWC for long haul high data rate applications. This system is designed using differential quadrature phase shift keying (DQPSK) through inter-satellite optical wireless communication (IsOWC) channel. The verification of the performance is performed at bit rates of 100 and 200 Gbps over a space distance range up to 1000 to 50000 km under different transmitted power. The simulative investigation has been carried out in terms of important parameters like BER, Q-factor and eye diagrams.

Self-phase modulation (SPM) is one of the major non-linear effect in single-tone radio over fiber system which limits the long-distance transmission as it leads to the broadening of pulse spectrum. In this paper, the mathematical and parametric analysis was carried out to understand the origination and upgradation of SPM and based on results achieved, a rigorous evaluation has been conducted to decrease the impact of SPM. The effect of SPM has been evaluated in terms of optical spectrums, eye diagrams, eye-opening and Q-factor by utilizing four important parameters specifically launched power, fiber effective area, bit rate and fiber attenuation using OptiSystem simulator which reveals insight information for the elimination of non-linear effects.

Passive optical network (PON) supported orthogonal frequency division multiplexing is a network that is designed for subsequent generation of optical networks. During this work, the proposed algorithm consists of neurofuzzy rules which update and control the minimum bandwidth allocation granularity g\left( g \right). In order to improve the quality of service, a biogeography-based optimization algorithm is introduced and a new fitness function is proposed which reduces the round trip time by enhancing the distribution scaling factor. Hence, the proposed work reduces the jitter and increases the throughput of the PON for fixed g=1g = 1 which enhances the network performance by 3.4 % and 1.23 %, respectively.

Linear electro-optic effect or Pockels effect is not only a very effective way to control the intensity or phase of a propagating radiation but it can also be used to generate a low-frequency electronic signal. Low-frequency electronic signal is useful in many real-world applications like bio-medical, signal processing, gravitational wave detection, etc. In this paper, the authors proposed a scheme for generation of time bound low-frequency electronic signal using multi-passing scheme of light through a Pockels cell with sawtooth electrical biasing. The Pockels cell is used in an amplitude modulation scheme.

Spectral amplitude coding optical code division multiple access (SAC-OCDMA) is one of the most important multiplexing schemes of OCDMA that has turned out to be a stimulating investigating area in optical communication due to its increased privacy, network capacity and its flexibility in allocating the channels and asynchronous environment. On the other hand, Inter-satellite optical wireless communication (IsOWC) which is a favorable area of research in optical communication is useful for bursty transmissions and long-distance communications. In this paper, we have designed a hybrid SAC-OCDMA system through IsOWC channel using ZCC code for advanced intensity modulation formats (CSRZ, Db, and AMI). The investigation is done for four users at a bit rate of 40(4×10) Gb/s using a direct detection technique. Further, on comparing the proposed system using advanced intensity modulation formats, the result shows that system using CSRZ format is better in terms of BER, Q-factor, SNR and the eye diagram with respect to AMI and Db.