Volume 38, Issue 1 -

In this paper, the simulative analysis of an inter-aircraft optical wireless communication (IaOWC) system has been presented using different system parameters and the performance of the system has been enhanced by the application of EDFA amplifier at the receiver end. A link range of 110 km at 2.5 Gbps has been achieved with same BER performance resulting in the performance enhancement of 47 % when compared to previous detection mechanism.

Optical time-division multiplexing (OTDM) updates the well-known technique of electrical time-division multiplexing into the optical domain. In OTDM, optical data streams are constructed by multiplexing a number of low bit-rate optical streams in time domain. In this paper, the performance of eight channel OTDM system is analyzed and compared for different modulators such as EAM, MZM and AM with Symmetric Mach–Zehnder demultiplexing switch at bit rate of 20 Gbps. The effect of input signal power on BER, Q-factor and received optical output power has been evaluated. It is observed that EAM, MZM and AM provide acceptable Q-factor of 7.70, 7.50, 6.69 and BER of 2.55×10 −16 , 1.15×10 −15 , 4.33×10 −13 , respectively at 5 dBm transmission power. Furthermore, it is found that EAM is more superior as compared to MZM and AM.

The article explores performance investigation for the all optical AND logic gate at the 200 Gbps data rate. Numerical simulations have been executed and output pattern for the AND logic operation has been verified. Accordingly good extinction ratio of 15.8 dB has been observed. Investigations depict optimum optical performance metric with the key deign parameters as the pump power (>1e-4 W), pump current (>1 ‎Å), current injection efficiency (>0.5), modulator bias voltage (>1.25 V), modulator on off ratio (>10 dB) and the SOA reflectivity (>0 dB). The schematic is evident, simpler tender’s option to endow different input combinations simultaneously. Furthermore, the outcomes are well sustainable to formulate forthcoming advanced higher data rate all-optical digital processing.

In the present paper, radio-over-fiber (RoF) technology has been proposed, which is the integration of the optical and radio networks. With a high transmission capacity, comparatively low cost and low attenuation, optical fiber provides an ideal solution for accomplishing the interconnections. In addition, a radio system enables the significant mobility, flexibility and easy access. Therefore, the system integration can meet the increasing demands of subscribers for voice, data and multimedia services that require the access network to support high data rates at any time and any place inexpensively. RoF has the potentiality to the backbone of the wireless access network and it has gained significant momentum in the last decade as a potential last-mile access scheme. This paper gives the comprehensive review of RoF technology used in the communication system. Concept, applications, advantages and limitations of RoF technology are also discussed in this paper.

In the past decades, optical fiber has been widely used in communication system owing to low transmission losses, large information carrying capacity, small size, immunity to electrical interference and increased signal security. Focusing on increasing the network transmission capacity, control on the quality of transmission was the field that withdraws attention of research community. For this reason, fiber losses and their compensation remain the important design issue. In the present work, an effort is put in to design a system capable of doing error analysis of system for power losses taking place in the presence of attenuation effect. Attenuation is one of the important phenomena that determine the maximum possible distance between a transmitter and receiver or quantity and position of amplifiers and repeaters in optical networks. The mathematical model equations are obtained representing variation trends of bit error rate BER and Q -value with varying attenuation, which has been verified by different wavelength sources and network conditions.

Analysis is carried out for a single span wavelength division multiplexing (WDM) transmission system with distributed Raman amplification to find the effect of amplifier induced crosstalk on the bit error rate (BER) with different system parameters. The results are evaluated in terms of crosstalk power induced in a WDM channel due to Raman amplification, optical signal to crosstalk ratio (OSCR) and BER at any distance for different pump power and number of WDM channels. The results show that the WDM system suffers power penalty due to crosstalk which is significant at higher pump power, higher channel separation and number of WDM channel. It is noticed that at a BER 10 −9 , the power penalty is 8.7 dB and 10.5 dB for the length of 180 km and number of WDM channel N =32 and 64 respectively when the pump power is 20 mW and is higher at high pump power. Analytical results are validated by simulation.

We propose the experiment transport of 48 Chs 40 Gb/s dense wavelength division multiplexing (DWDM) system that uses larger effective area fiber (LEAF) in combination with reverse dispersion fiber (RDF), which is a dispersion compensation device, in C band (1,530–1,560 nm) and L band (1,570–1,610 nm) wavelength range to solve the dispersion program. The single Mach–Zehnder modulation (MZM) format with erbium-doped fiber amplifier (EDFA) configuration to generate return-to-zero differential phase-shift keying (RZ-DPSK) modulation signal can compensate dispersion impairment in 48×40 Gb/s DWDM system. The proposed 48×40 Gb/s DWDM system successfully employs single MZM RZ-DPSK modulation format to reduce modulation complex configuration with EDFA to promote the power signal and using LEAF and RDF in 28 spans over 3,360 km ultra-long-haul fiber transmission successfully.

Coherent optical systems have relatively high laser phase noise, which affects the performance of forward error correction (FEC) codes. In this paper, we propose a method for selecting Bose–Chaudhuri–Hocquenghem (BCH) codes for coherent systems with star-shaped constellations and M -ary differential quadrature amplitude modulation (DQAM). Our method supports constellations of any order M which is a power of 2, and includes differential M -ary phase shift keying as a special case. Our approach is straightforward, requiring only short pre-FEC simulations to parameterize a statistical model, based on which we select codes analytically. It is applicable to pre-FEC bit error rates (BERs) of around 10 −3 . We evaluate the accuracy of our approach using numerical simulations. For a target post-FEC BER of 10 −5 , codes selected with our method yield BERs within 2× target. Lastly, we extend our method to systems with interleaving, which enables us to use codes with lower overhead.

This paper presents a comprehensive review of successive interference cancellation (SIC) scheme using pulse position modulation (PPM) for optical code division multiple access (OCDMA) systems. SIC scheme focuses on high-intensity signal, which will be selected after all users were detected, and then it will be subtracted from the overall received signal, hence, generating a new received signal. This process continues till all users eliminated one by one have been detected. It is shown that the random location of the sequences due to PPM encoding can reduce the probability of concentrated buildup of the pulse overlap in any one-slot time, and support SIC to easily remove the effect of the strongest signal at each stage of the cancellation process. The system bit error rate (BER) performance with modified quadratic congruence (MQC) codes used as signature sequence has been investigated. A detailed theoretical analysis of proposed system taking into account the impact of imperfect interference cancellation, the loss produced from the splitting during encoding and decoding, the channel loss and multiple access interference is presented. Results show that under average effective power constraint optical CDMA system using SIC scheme with M -ary PPM modulation outperforms conventional correlator detector and SIC scheme with on–off keying (OOK) modulation.

In this paper, inter-satellite optical wireless communication (IsOWC) system is proposed, one of the imperative utilizations of free space optics/wireless space optics (FSO)/WSO innovation. IsOWC frameworks give a high bandwidth, small size, small weight, low power and minimal effort different option for present microwave satellite frameworks. Optical communications systems have evolved from lengthy fibers to powerful wireless system. This has hence resulted in the use of optical wireless communication system in space communications. As the quantity of satellites circling the Earth expands year by year, a system between the satellites gives a strategy to them to correspond with one another. This is vital for satellites to send data to each other furthermore to hand off the data starting with one satellite then onto the next satellite and after that to the ground stations. By utilizing laser satellite correspondence, the satellites can be joined with information rates up to a few Gbps. The system performance including bit rates, input power, wavelength and distance on an inter-satellite link was analyzed. Various issues such as bit rates, input power, wavelength and distance were presented in IsOWC.

We propose the experimental transport of 48 channels with 40 Gbit/s dense wavelength-division multiplexing (DWDM) system that uses single-mode fiber (SMF) in combination with dispersion compensation fiber (DCF) which is a dispersion compensation device, in C and L band wavelength range to solve the dispersion program. The DWDM system scheme employing single Mach–Zehnder modulation (MZM) return-to-zero differential phase-shift keying (RZ-DPSK) modulation format with hybrid Raman/EDFA (Erbium-doped fiber amplifier) configuration to improve transmission signal, and employing an optical phase conjugation (OPC) configuration in the middle line. That can compensate for dispersion impairment and improve nonlinear effects to investigate transmission distance performances.

This manuscript deals with analysis of Spectral Amplitude Coding Optical Code Division Multiple Access (SACOCDMA) system. The major noise source in optical CDMA is co-channel interference from other users known as multiple access interference (MAI). The system performance in terms of bit error rate (BER) degrades as a result of increased MAI. It is perceived that number of users and type of codes used for optical system directly decide the performance of system. MAI can be restricted by efficient designing of optical codes and implementing them with unique architecture to accommodate more number of users. Hence, it is a necessity to design a technique like spectral direct detection (SDD) technique with modified double weight code, which can provide better cardinality and good correlation property.

In graded index fiber, some degree of ellipticity is found. So it is important to study the effect which is little bit different from circularity. With the help of a new method illustrated in this paper, the core fields in case of non-circular profile can be written in a more simple way. The convenient feature of this method is that mode patterns can be found by simple analysis of algebraic equations. Ray path propagations in graded non-circular fibers were already studied by researchers. However, we provide the analysis of mode field using Wentzel–Kramers–Brillouin (WKB) method. In our analysis, the core fields of step index fibers are considered assuming the elliptical core-cladding interface followed by the limiting cases with focus approaches to infinity and focus approaches to zero. Finally, modes for parabolic profile with circular refractive index are discussed with the concept of bounded and leaky modes. The convenient feature of this method is that mode patterns can be analytically studied. In this paper, the main focus is also on the experimental characteristic of optical communication link and of their components. We give an introduction to optical fiber systems and various phenomena related to it. The phenomena of attenuation and dispersion are discussed elaborately and details are provided through experimental observation and verification. All the details about various topics mentioned above are concluded and verified through experiments. This type of an arbitrary optical waveguide structure has a vast application in microwave engineering where the high-speed Mach–Zehnder modulator is going to deployed.

In this article, for an optical star wavelength division multiplexing (WDM) network, with quality factor ( Q -factor) as performance metric, we investigate the performance degradation due to the combined effects of four-wave mixing (FWM) and amplified spontaneous emission (ASE) noise. A mathematical model is developed, and the simulations are performed based on the optical frequency grid defined by the ITU-T Recommendation G.692. Further, the analysis is conducted for the optical fibers that are ITU-T compliant viz. G.652, G. 652D, G. 653, G. 654 and G.655. The simulation results show that, compared to the other fiber types, performance of the G. 652D and G.652 fibers is the “best”, thus justifying the preferred use of fibers with high dispersion and effective area values. The simulation results also highlight that with the use of a fiber having low dispersion and effective area value, it may not be possible to obtain the desired performance.