Volume 47, Issue 1

This paper indicated the high speed preamplifier circuits based bipolar/field effect transistors for the optimum photodiode receiver’s performance in optical communication system. The total photodiode bandwidth is studied against photodiode capacitance and input photodiode resistance. The total photodiode bandwidth is demonstrated against photodiode capacitance and ambient temperature variations. The total photodiode spectral/thermal noise density is clarified versus the photodiode based bipolar/FET transistor and ambient temperature variations. The total photodiode transconductance, optimum photodiode gain and the optimum photodiode signal per noise ratio are analyzed and clarified against the photodiode based bipolar/FET transistor and ambient temperature variations at various input photodiode resistance. Bit error rate at receiver is demonstrated versus the photodiode based bipolar/FET transistor and input photodiode resistance variations at various ambient temperature.

This paper highlights the different optical fiber hybrid repeater amplifiers arrangement for optical losses and optical dispersion management in the presence of modulation code schemes. The light signal power is measured and clarified with/without any amplification versus fiber channel length with 1,300 and 1,550 nm wavelength based on various modulation schemes. Electrical output power after receiver is clarified without amplification and with various amplification techniques against fiber channel length with second and third wavelength based on on-off keying modulation code scheme. The quality factor and BER are measured after receiver against transmission data rates without amplification and with various amplification techniques against 300 km fiber channel length with 1,300 nm wavelength based different modulation code schemes.

In this paper, an analytical method is presented to assess the performance of bit error rate (BER) of a DC biased optical orthogonal frequency division multiplexing (DCO-OFDM) SMF transmission with distributed Raman amplifier (DRA). Formulas are developed to determine the signal-to-noise ratio (SNR) at the output of a DCO-OFDM receiver and the bit error rate (BER) for an OFDM demodulator’s output. By considering the Gaussian probability density function (pdf) for the OFDM demodulator output, the average BER is calculated numerically. The results are presented based on receiver sensitivity, bit error rate and optical SNR at a given BER of 10 −9 , with variations in system parameters such as input signal power, data rate, fiber distance, modulation index and OFDM sub-channel number. A comparison of BER performance indicates that DC biased optical OFDM with intensity modulation direct detection (DCO-DD-OFDM) offers better receiver sensitivity compared to optical OFDM without DC bias at a BER of 10 −9 . Our analytical results align with the published findings on optical OFDM.

In this work cascaded Fabry–Perot spatial filter was constructed with two and three duals uniform apodised fiber Bragg gratings. The characteristics of the constructed filter were investigated in terms of the narrowest and widest full width at half maximum (FWHM) in pm, interferometer noise in dBm and OSNR in dB. Smoothing filter would be obtained in the case of three cascaded dual FBGs with the narrowest and widest FWHM achieved by the proposed structures are 123.128 pm and 286.88 pm, respectively, with −16 dBm and −18.4 dBm interferometer noise and 8.7 dB, 6.39 dB optical signal to noise ratio in dB for widest and highest band pass filter, respectively. Narrowest FWHM and in sometimes can be called bandwidth of the filter was obtained in the minimum amplification range (15 dBm) while and widest one in the case of 24 dBm. For three cascaded amplified Fabry–Perot band pass filter widening in the optical bandwidth of the was obtained with bandwidth of 163.752 pm. Narrowing bandwidth was 68.572 pm in the case of dual FBGs and 81.323 pm in the case of single Fabry–Perot. Narrow pulse duration of 20 us of the transmitted spectrum was obtained in the case of three cascaded Fabry–Perot with 24 dBm nonlinear EDFA at 15 V P-P.

Intensity modulation (IM) formats are the legacy formats which are continuing to act as modulation formats of interest in fiber optic communication systems and optical networks. The IM formats have become formats of interest in free space optic communication (FSO) systems due to its simple generation and detection principle, thus making FSO system economical and easier to handle/operate under adverse and random characteristics of atmospheric channel. This paper compares the performance of different IM formats (with memory and without memory or memoryless). The IM formats considered here are non return to zero (NRZ), return to zero (RZ), carrier suppressed RZ (CSRZ), vestigial side band CSRZ (VSB-CSRZ), duobinary RZ (DRZ) and modified duobinary RZ (MDRZ). The comparative analysis investigates the effect of launch power and length of FSO channel at different data rates of 10 Gb/s and 40 Gb/s for single channel FSO system, with the help of simulations. The results discussed, depicts that VSB-CSRZ outperforms other modulation formats at 10 Gb/s and duobinary format has shown lesser degradation in system performance when bit rate increases from 10 Gb/s to 40 Gb/s.

In large-scale tiled chip multiprocessors (TCMPs), network-on-chip (NoC) is a prevalent interconnect solution. The NoC router plays a crucial role in NoC architecture, and two primary types exist: buffered and bufferless. The latter offers a promising solution due to its streamlined design, reduced energy consumption, and hardware efficiency. This paper proposes a 2D 4 × 4 mesh NoC architecture with a novel bufferless NoC router design using XY routing algorithm. The proposed mesh network consists of routers and processing elements, with each router connected to its four adjacent peers (North, South, East, and West) and a single processing element. The proposed router design eliminates the input buffers, output buffers and crossbar switch. The novel bufferless NoC router architecture comprises of various functional blocks, including ejection and injection controllers and Data ranking based on port prioritization, and age incrementor which efficiently solves long critical path issues by dynamically changing the port priority and hence solves the deadlock issue. By leveraging efficient routing and prioritization mechanisms, the novel architecture facilitates the seamless flow of flits through the network. Optical NoCs are based on optical interconnects and optical routers, and have significant bandwidth and power advantages. Our results indicate that the proposed bufferless router can lead to significant area (30.3 %) reduction over the standard BLESS.

All-optical basic logic gates play a pivotal role in the development of ultra-fast and energy-efficient computing systems. In this communication, we have designed an alternative method of all-optical logic OR, AND, XOR, and XNOR gates using 2-dimensional photonic crystals with a hexagonal lattice structure. The OptiFDTD software and finite-difference time-domain (FDTD) method has been used to verify the proposed designs and analyzed by calculating the contrast ratio and bit rate. The contrast ratios of the OR, AND, XOR, and XNOR gates are 43.20 dB, 36.40 dB, 41.46 dB and 37.63 dB, respectively. The output of the proposed logic gates may efficiently enhance the optical communication system.

Loss and dispersion are the major issues that need to be optimized for sustainable and effective optical communication. The lowest loss wavelength and best dispersion-managed wavelength are partially conjugated by dispersion shifted fiber (DSF), dispersion flattened fiber (DFF), and different modulation techniques. In search of further simple and effective alternatives to compensate for both the loss and dispersion of optical fiber, we have considered some commercially available optical fiber friendly materials like pure SiO 2 , B 2 O 3 , P 2 O 5 and GeO 2 doped SiO 2 along with some popular fluoride glass combinations known as ZBLAN, HBL, ABCY, ZBLA, ZBG. Our study on material dispersion of some pure and doped materials has brought out some exciting results regarding the optimized loss-dispersion conjugation. It is observed that the systematic applications of the compositions can replace the existing DSF and DFF. At the same time, the efficiency of DSF and DFF can be increased by using these fiber materials as well. The technique can be used to boost the efficiency of existing loss-dispersion management systems by selectively replacing the materials of those systems. Our significant report on the fundamental properties of various fibers and their materials has a visionary direction toward loss-dispersion management.

This article reports the computation of impedance in dual wavelength quantum cascade lasers (DW-QCLs) for the first time. The DW-QCL operates at two wavelengths 10.5 μm and 8.9 μm and contains 48 stages. The injected current decides the single mode (emission at 10.5 μm) or bi-mode (emission at both wavelengths) lasing characteristics of the device. The device exhibits a higher impedance till I th (1) since lasing has not begun and sharply reduces from 18.8 Ω (at 0.5 I th (1) ) to 1.2 Ω at I th (1) at dc conditions. Under pre-threshold lasing region, the device exhibits a larger impedance and is inductive in nature. The maximum magnitude of impedance in this region is 18.82 Ω when the device is injected with 0.5I th (1) and it reduces to 10.45 Ω at 0.9I th (1) . In the lasing region (single and bi-mode), it is clearly visible that there are regions of capacitive reactance and inductive reactance occurring at different bands. The maximum impedance offered by the device over a wide range of frequencies is computed for different modes of operation. The analytical part to derive the equation of impedance of the DW-QCL involves the rate equations in frequency domain, the apparent substitution and simplification thereafter. The computation of impedance is necessary for matching the laser driver with the DW-QCL for efficient operation at higher operating frequencies.

In this study, the theoretical model of in-band pumped holmium-doped fluoride fiber laser was numerically investigated. A holmium-doped fluoride fiber is promoted for laser operating at 2.1 µm. The proposed model is based on the fundamental properties of a holmium doped fluoroindate glasses and parameters obtained from the previously published results. The model was simulated via a cladding pumped system at 2.051 µm pumping wavelength. Good validation between the suggested model with the previously published experimental measurements was achieved with considering the main transfer processes such as energy up-conversion transition and cross relaxation process. The numerical analysis indicated that the energy transfer up-conversion has a negative effect on the laser performance while the cross relaxation process causes significant enhancement on the performance of in-band pumped holmium doped fluoride fiber laser.

Light Fidelity (LiFi) based on data transfer with visible light offers a more profound solution to the wireless communication paradigms. This study brings focus on how the line-of-sight (LOS) channel can be used to enhance the performance of a LiFi network. We discuss the LOS channel characteristics, system features, and deployment considerations with respect to evolution and prospects. Experimental modelling and conditions testing involve Q-factor, bit error rate (BER) and data rates analysis. The results presented in this study suggest that both the characteristics of channels and the data transmitted affect the efficiency of the network; higher data rates and longer distances lead to increased BER and lower Q-factor. The outcome of this study reveals key factors which influence the channel performance and provides a guideline that would be beneficial in advancing the LiFi system implementation for different applications. It is hoped that the findings of this study are useful for network engineers and researchers to design better and more flexible LiFi systems for various communication applications.

This paper demonstrated the high capacity performance signature of micro optical mechanical system switches based fiber Bragg grating scheme in optical wavelength division multiplexing data routed center networks. The FBG reflectivity is simulated versus near infrared operating wavelength region with relative refractive index difference of Δ n  = 0.1 %. Required optical pump power, temperature increment and FBG power dissipation or consumption are demonstrated versus FBG wavelength spacing at pumping wavelength of 1,480 nm for doped/undoped fiber. Required FBG mechanical switching voltage, and required FBG mechanical/thermal switching time are clarified at pumping wavelength of 1,480 nm for doped/undoped fiber. Grating period and Bragg wavelength is studied against effective refractive silica/polymer FBG index.

Free Space Optics (FSO) is an innovative optical communication technology that leverages light propagation in free space for direct line-of-sight interactions. This technology is characterized by several benefits, including secure transmission, high bandwidth, and rapid data transfer rates, making it a promising candidate for integration into emerging 6G networks. However, the efficiency of FSO systems is adversely affected by various weather conditions, such as rain, temperature fluctuations, snow, and fog, as well as atmospheric disturbances. This paper presents a Particle Swarm Optimization (PSO)-based approach to optimize the divergence angle of FSO systems. PSO is a type of artificial intelligence that excels at managing complex settings and adapting to changes in the environment, thus making FSO systems more robust against such challenges. By optimizing this critical parameter, the proposed method significantly improves the reliability and efficiency of data transmission in FSO systems, supporting the advanced performance demands of future 6G networks. This optimization ensures FSO systems can achieve faster and more reliable connectivity, essential for the next generation of wireless communication.

This study focuses on optimizing machining parameters for A713 aluminum alloy, renowned for its high strength-to-weight ratio but challenging to machine with precision. Using the Taguchi method, key parameters – cutting speed, feed rate, and depth of cut – are optimized to improve surface finish, tool life, and dimensional accuracy. An L9 orthogonal array is applied to enhance experimental efficiency. Furthermore, the integration of Passive Optical Network (PON) technology facilitates real-time data monitoring and transmission, enabling continuous feedback and timely adjustments. This hybrid approach of Taguchi optimization and PON technology achieves superior machining performance, boosting surface quality and operational efficiency. The research highlights how modern data transmission solutions like PON can enhance traditional optimization methods, providing a scalable framework for advanced machining processes in industrial applications.

Software defined networking (SDN) is a communications methodology that centralizes network management and programmability resulting in more flexible network administration. This project aims to configure and simulate a software-defined network to implement customized, dynamically-assigned flow control rules between network nodes – replacing static routes. We consider virtual network embedding (VNE) in development of network routing algorithms. Through this project, we seek to demonstrate the feasibility and benefits of SDN-based network control for diverse systems, enhancing adaptability and efficiency in managing communication between diverse network nodes. The proposed work is crucial for advancing adaptive, efficient, and scalable communication systems, enabling dynamic resource management, enhanced interoperability, and supporting next-generation technologies like six generation (6G) and IoT seamlessly.

The rapid growth of high-data-rate applications necessitates the development of new communication frameworks since bandwidth constraints for data-intensive applications hinder traditional networks and conventional microwave/radio frequency (RF) communications. This study explores a hybrid communication link that combines fiber-to-the-x (FTTx) and free-space optical (FSO) technologies, utilizing ultra-dense wavelength-division multiple access (UD-WDMA) with a channel spacing of 0.2 nm/25 GHz, under various weather conditions. Based on bit error rate (BER), optical signal-to-noise ratio (OSNR), and quality factor (QF), the performance of the suggested FSO-FTTx system was examined. The system performed well in diverse weather conditions, achieving a minimum BER of ≤10 −5 , QF values of 4 or higher, and OSNR levels between 10 and 20 dB. The proposed system successfully transmitted a data rate of 1.28 Tbps over 35 km in single-mode fiber (SMF), accommodating different FSO link ranges despite varying weather conditions. However, performance fluctuations were observed under adverse conditions, with attenuation ranging from 0.91 dB/km in extremely light mist to 273.39 dB/km in dense fog, impacting the FSO link range. The findings underscore the proposed hybrid system’s potential to enhance optical wireless communication for high data rates, making it promising for beyond 5G and early 6G applications.

In this paper, the performance of 300 × 10 super dense wavelength division multiplexing (SD-WDM) system has been evaluated with unequal channel spacing. Further, evaluation is carried out for the proposed system to consider the effect of different modulation formats, input power, and high speed data rate. Massive impression is recorded by RZ modulation format with the support of Raman-EDFA hybrid optical amplifier (HOA) for acceptable characteristics of super dense communication system.

This paper provides a system architecture to evaluate the results of high dynamic range orthogonal frequency division multiplexing (OFDM) as a technique to transfer the 64-quadrature amplitude modulation (QAM) basebands signal over fiber, for the signals of the fifth generation/new radio (5G/NR) broadcasting at 28 GHz suitable for millimeter wave (mm-wave) applications. With this radio-over-fiber (RoF) system, the Optiwave Opti-system software (2024) is used for the assessment research. The integration of 64QAM-OFDM and RoF methods has led to a reduction in wireless network costs while maintaining a high data rate. This paper shows the RoF system design, for a 100 MHz 5G/NR signal broadcast at 28 GHz, results the largest dynamic range for millimeter wave applications. With an optical modulator design of the IF and LO signals, 64-QAM OFDM is possible. Better dynamic range may be achieved by using this approach to eliminate the error in optical bands before the photo recognition process. The optical spectrum of the transmitted signal, signal to noise ratio (SNR), error vector magnitude (EVM), and the cancelation diagram serve as the foundation for the performance analysis. Based on the acquired results, the system that is being presented is a strong contender for mobile communication systems in the context of 5G and beyond.

The Wavelength Division Multiplexing Passive Optical Network (WDM-PON) is considered a highly promising option for next-generation optical access networks. In this work, we propose and demonstrate a WDM-PON network architecture using colorless Optical Network Units (ONUs). Our design employs a single broadband source (comb source) to generate the optical carriers required for bidirectional transmission. We demonstrate the feasibility of implementing a WDM-PON over a 30 km standard single-mode fiber (SSMF-28), with downstream transmission at 640 Gbps and upstream at 160 Gbps. The proposed method involves comparing two WDM-PON networks with 16 channels, which have similar characteristics. In the first system, we use 32 carriers – 16 for downstream and 16 for upstream – while in the second system, only 16 carriers are used for both directions. In addition, this configuration allows us to easily double the total bandwidth of the network by increasing the number of ONUs to 32 and incorporating the unused carriers (the 16 other unused carriers from the second configuration).

The exponential growth in demand for high-capacity optical systems has driven the advancement of advanced modulation formats to upgrade transmission capacity and transmission quality. Effective fault diagnosis and self-configuration in inter-satellite optical wireless communication systems (IsOWCS) depend intensely on the generated data. Machine learning (ML) approaches offer promising solutions in evaluating the execution of these networks. In this study, a dataset was created using OptiSystem 18.0. The dataset was composed of various modulation formats such as duobinary, return-to-zero (RZ), non-return-to-zero (NRZ), 33 % RZ, chirped NRZ, vestigial sideband (VSB) NRZ, carrier-suppressed return-to-zero (CSRZ), and VSB CSRZ. The classification of modulation formats has been presented in this study using ML. The dataset was created by varying input power from 0 to 20 dBm and evaluating parameters such as Q factor, input/output signal-to-noise ratio (SNR), power, range, eye closure, amplitude, height, eye opening, output OSNR. Four ML classifiers were used to predict the classification of different modulation formats. Random forest (RF) classifier performed exceptionally well and achieved 100 % accuracy. Moreover, an interactive user-friendly web page was also developed using Anvil for modulation format classification. The proposed research underscores the significance of selecting the appropriate modulation format to optimize the performance and transmission distance of IsOWCS, subsequently enhancing the operation of high-speed optical communication systems.

The present study involves an examination of a communication system known as radio over free space optics (RoFSO), which was designed using Optisystem ver. 20. The main purpose of this inquiry is to analyze the transmission of data at a rate of 40 Gb/s over a link distance of 2 km. The achievement was attained by the utilization of four transmission channels, each of which has the capability to send data at a rate of 10 Gb/s. The system under consideration was evaluated through varying degrees of turbulence. Two scintillation models, log-normal and gamma–gamma, were used to evaluate the proposed communication performance and include evaluating the behavior of specific wavelengths (193.1, 193.2, 193.3, and 193.4 THz) in transmitting data. This evaluation is achieved by the metrics Q-factor, bit error rate (BER), and log BER. The suggested system’s data-transfer performance improved up to a distance of 1.75 km when the scintillation (L-N) model was applied, whereas it was limited to 0.75 km when the (G-G) model was imposed. Furthermore, it is noticed that the wavelength (193.1 THz) is distinct in data transfer across the two models, followed by the wavelength (193.4 THz). RoFSO is an emerging network architecture that holds significant potential for fulfilling the envisioned requirements for the advancement of 5G systems.

Using UAVs as relays in wireless communication offers several advantages like flexibility, coverage, line-of-sight communication, cost effectiveness, adaptability to changing network demands, etc. UAVs can perform surveillance, delivery, mapping, and disaster response. They offer real-time data collection, high maneuverability, and access to remote areas. In this manuscript, we consider a UAV-enabled dual hop mixed RF/FSO wireless communication system. The system includes a UAV acting as a decode-and-forward relay, facilitating communication from the base station (B) to multiple mobile users. The opportunistic scheduling scheme is used to select the user with the best instantaneous channel conditions, typically based on the highest signal-to-noise ratio (SNR) or lowest outage probability, to maximize throughput and ensure more reliable communication. The first hop from B to the UAV relay R, employs a free space optics (FSO) link modeled with gamma–gamma fading. The second hop, from R to multiple users, is a radio frequency (RF) link modeled with Rayleigh fading. The direct communication between base station and mobile users is not possible due to the blockage by various natural and man-made obstacles. We analyze the outage probability at high SNR values to gain further insights into system performance. Additionally, closed-form analytical expressions for the outage probability and average bit error rate (ABER) of the proposed system are derived.

The ability of the optical code division multiplexing approach to allow secure information transfer has sparked a great deal of interest in underwater wireless optical communication (UWOC). A weight managed zero cross correlation (WMZCC) code based UWOC system is presented delivering 5 users × 10 Gbps capacity under different ocean/sea conditions such as pure sea, clear ocean and coastal sea. The WMZCC code has least user interferences, mapping free code construction, weight managed, controlled code length, and less complexity. The performance comparisons between WMZCC codes and diagonal permutation shift (DPS) are established by considering Q factor as evaluation parameter and results revealed that performance of WMZCC is better than DPS due to ZCC code. Q factor values under pure sea at 13 m for WMZCC codes and DPS codes are 13.24 and 9.86 respectively. For 7.2 m UWOC link distance, Q factor values obtained are 13.1 and 10.2 in case of WMZCC and DPS respectively under coastal sea. On contrary, DPS has variable cross correlation and therefore experience more multiple access interference (MAI). The presented system successfully offered >20 % performance improvement in Q  factor as compared to DPS codes in UWOC.

The increasing demand for higher bandwidth and reliable communication networks driven by next-generation mobile technologies (5G/6G) and the Internet of Things (IoT) poses challenges for existing communication infrastructures. Free Space Optics (FSO) offers high-speed wireless data transmission comparable to fiber optics but suffers from significant performance degradation due to environmental factors such as rain, fog, and atmospheric turbulence. This study investigates the potential of a hybrid Dense Wavelength Division Multiplexing (DWDM)-FSO system to overcome these challenges. By combining DWDM’s high capacity with the flexibility of FSO links, the system achieves a data rate of 5.4 Tbps across 90 users. Simulations conducted using OptiSystem software evaluate the impact of different weather conditions – clear skies, heavy rain, and dense fog – on performance. Key metrics, including bit error rate (BER), quality factor (Q-factor), and eye diagrams, are analyzed to assess signal integrity and reliability. A comparative study of Single Input Single Output (SISO) and MIMO configurations (2 × 2 and 3 × 3) shows that the 3 × 3 MIMO-FSO setup significantly enhances performance, maintaining signal quality and extending range under adverse weather. These findings highlight the hybrid DWDM-FSO system’s potential to deliver high-speed, resilient communication, ensuring seamless connectivity in dynamic environments.

The present paper analyzes the performance of vehicle-to-vehicle (V2V) visible light communication (VLC) systems across various practical scenarios. Metrics including bit error rate (BER), frequency response, signal-to-noise ratio (SNR), channel capacity, and time delay are analyzed for three distinct scenarios. Results indicate that inadequate lateral displacement between vehicles of adjacent lanes can significantly impact BER performance. Moreover, frequency response analysis reveals undesirable periodic variations in scenario-2, posing challenges for V2V communication. In the case of non-line-of-sight (NLoS) communication (scenario-3), both longitudinal and lateral displacements exhibit notable impacts across all analyzed metrics.