Abstract The need for high capacity optical communication networks has driven the development of dense wavelength division multiplexing (DWDM) as an important technology. Chromatic dispersion is one of the severe impairments that affect the transmission performance by causing pulse broadening, intersymbol interference (ISI), and higher BER, however. In this paper, a hybrid of dispersion compensating (DCF) and Bragg grating (FBG) dispersion compensation technique is proposed and studied to improve the performance of DWDM optical communication system. The proposed system was simulated and the performance metrics such as quality factor ( Q -factor). For a transmission distance of 160 km, the proposed hybrid scheme obtained a value of the Q factor of ∼7, while the value of the Q factor for FBG, DCF, and uncompensated system was ∼4.2, ∼2.2, and ∼0.8, respectively. Furthermore, the BER was reduced to 10 −8 , while the FBG-only, DCF-only, and uncompensated systems achieved BER values of 10 −7 , 5 × 10 −7 , and 10 −6 , respectively. In addition, the hybrid configuration provided the highest OSNR of approximately 28 dB, representing a significant improvement over FBG (22 dB), DCF (18 dB), and the uncompensated system (12 dB). The results achieved show that the combination of FBG and DCF can be used to achieve effective chromatic dispersion mitigation and obtain better signal quality; the proposed hybrid compensation technique is a potential solution for future high capacity and long-haul DWDM optical communication system.
Abstract The high peak-to-average power ratio (PAPR) remains one of the major challenges affecting asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) systems used in visible light communication (VLC). Although transform precoding techniques such as discrete Hartley transform (DHT) precoding can effectively reduce PAPR, their computational complexity increases significantly as the number of subcarriers increases, limiting practical implementation in large-scale systems. In this paper, a grouped discrete Hartley transform (G-DHT) precoding scheme is proposed for low-complexity PAPR reduction in ACO-OFDM systems. The proposed technique partitions the input symbol vector into smaller groups and independently applies DHT precoding within each group before OFDM modulation. This significantly reduces computational complexity while preserving the PAPR reduction capability of conventional DHT precoding. Simulation results show that the proposed scheme achieves measurable PAPR reduction without noticeable bit error rate (BER) degradation. At a complementary cumulative distribution function (CCDF) of 10 −3 , the proposed G-DHT scheme with group size G = 128 achieves approximately 0.95 dB PAPR reduction relative to conventional ACO-OFDM while reducing computational complexity by about 50 % compared with full DHT precoding. The results indicate that grouped DHT precoding provides an effective trade-off between PAPR reduction performance and implementation complexity in optical OFDM systems.
Abstract The need for high capacity optical networks has led to the stronger drive for efficient techniques to counteract the impairments of the optical transmission medium in Dense Wavelength Division Multiplexing (DWDM) systems. Some of main factors that set the limit of transmission distance and affect the quality of signal in a high-speed optical communication link are the chromatic dispersion and attenuation. In this paper, the design and performance optimization of a hybrid DWDM optical communication system have been presented that uses Fiber Bragg Grating (FBG) for chromatic dispersion compensation and Erbium-Doped Fiber Amplifiers (EDFAs) for optical power enhancement. Multiple DWDM channels (25 Gb/s and 100 GHz channel spacing) are transmitted through a 50 km Single-Mode Fiber (SMF) link and the designed system is implemented and analyzed in the OptiSystem. The ideal WDM multiplexer/demultiplexer is used to enable wavelength multiplexing, and optical spectrum analyzers, BER analyzers and eye diagram analyzers are employed to evaluate system performance.
Abstract This paper presents a dual-polarized Pulse Amplitude Modulation-4 (PAM-4) based inter-satellite optical wireless communication (IsOWC) system achieving 100 Gbps aggregate data rate using an 850 nm laser. Two orthogonally polarized beams each carry 50 Gbps, enabling spectrally efficient transmission over ranges of 8,000–20,000 km. System performance is evaluated using log(BER), EVM%, and eye diagrams across three parametric studies: receiver aperture diameter (10, 12, 15 cm), additional channel losses (5, 7, 9 dB), and laser transmission power (26, 28, 30 dBm) under pointing errors of 1–2 μrad. Results demonstrate that larger apertures and higher transmission powers significantly improve link performance, while pointing error proves a critical limiting factor at extended ranges. The proposed architecture offers a viable solution for next-generation high-throughput IsOWC systems.
Abstract This paper presents a comprehensive investigation of a high-capacity free-space optical (FSO) transmission system integrating intensity in-phase and quadrature modulation (IQM), orbital angular momentum (OAM) multiplexing, polarization division multiplexing (PDM), and orthogonal frequency division multiplexing (OFDM) techniques. The proposed 640 Gbps IQM-OAM-PDM-OFDM-enabled FSO system was evaluated under realistic atmospheric conditions of Riyadh and Jazan, Saudi Arabia, using year-long hourly meteorological visibility data from 2023. Three empirical attenuation models namely Kim, Kruse, and Al-Naboulsi were employed, yielding mean attenuation coefficients of 0.59–0.64 dB/km under Kim/Kruse and 2.03–2.06 dB/km under Al-Naboulsi, with peak attenuation reaching 169.80 dB/km in Riyadh and 348.70 dB/km in Jazan during severe dust and haze events. The integrated system achieves maximum transmission ranges of 15 km under the Kim and Kruse models and 7.25 km under the Al-Naboulsi model in both cities, a 52 % reduction in reliable range under worst-case versus typical conditions while maintaining pre-FEC BER of approximately 2.46 × 10 −3 (log 10 BER = −2.61), post-FEC BER below 10 −9 , and EVM around 14 % at maximum distance. Compared to a standalone OAM-FSO system, the proposed multi-domain architecture delivers a 16-fold capacity increase and an 87.5 % improvement in transmission range, demonstrating its suitability for resilient high-capacity FSO deployment across diverse Saudi Arabian climates.
Abstract In this paper impact of different heterogeneous core configurations have been analyzed to obtain low values of crosstalk and peak bending radius over the S + C + L wavelength band in multicore fiber with standard cladding diameter. Heterogeneous multicore fibers having 6-core, 8-core, 10-core, and 12-core within standard cladding diameter have been designed and simulated. The design optimization of the heterogeneous core configuration, results in the suppression of crosstalk value below −41.25 dB/km over the S + C + L wavelength band and peak bending radius value 10 mm of the 12-core MCF . The designed standard cladding diameter based high density heterogeneous MCF s have potential application in wideband space division multiplexing ( WB-SDM ) transmission systems.
Abstract Recent studies show that global Passive Optical Network (PON) deployments will reach over 1.3 billion subscribers by 2030in Optical Network Unit (ONU) device integration. Despite this, legacy systems suffer from scalability bottlenecks and average latency increments of 15–30 % during user density surges. Existing networks face significant challenges, such as latency spikes at the Optical Line Terminal (OLT) during ONU scalability and insufficient reliability in handling anomalies within converged infrastructures. To address these issues, a novel Multi-Armed Bandit (MAB) approach is applied to optimize dynamic bandwidth allocation (DBA) at the ONU layer, enabling increased user density without inducing latency burdens at the OLT. The MAB-based selection strategy efficiently adapts to varying traffic patterns by learning optimal resource assignment policies in real time, ensuring minimal contention delays and better quality of service (QoS). Network fault tolerance and reliability are enhanced through a Deep Q-Auto Encoder (DQAE)-based anomaly detection model trained to recognize and classify failure signatures across optical and packet layers. This unsupervised deep reinforcement learning model integrates reconstruction loss with Q-learning to identify unknown failure states simultaneously and recommend proactive recovery actions. The combined strategy improves user scalability and service stability and establishes a fault-resilient infrastructure suitable for next-generation converged optical networks.
Abstract This paper has demonstrated the simulative study of the multi mode step index/graded index fiber configurations based plastic core silica clad fibers with high speed light sources employment for indoor optical fiber system applications. The optical power is measured effectively after multi mode fiber against multi mode fiber link length with various laser operating wavelengths based on both NRZ (non return to zero) and RZ (return to zero) line coding. The optical signal per noise ratio is demonstrated through MMF based step index or graded index fibers versus transmission data rates for various operating laser wavelength based NRZ line coding. Possible data rate transmission is clarified against various fiber types based on different light sources for different operating laser wavelength based NRZ line coding. Max. Q factor and minimum bit error rate (BER) at receiver side against fiber link length for both multi mode step index and graded index fibers at 650 nm operating laser wavelength and various data rate transmission in the presence of NRZ line coding.
Abstract In this paper, multi-wavelength slicing was investigated by employing chirp fiber Bragg gratings (CFBGs) under varied mechanical forces, The CFBGs exhibited multi reflections regions so, the obtained results showed generation 30 spectral lines with 0.8 nm channel spacing by slicing a broadband source over a wavelength range from 1,528 to 1,563 nm with a maximum optical signal to noise ratio (OSNR) of 21 dB was obtained at 1,558 nm. The band rejection is 10 nm around the central wavelength of CFBGs. The 30 optical lines are divided into two regions, each side having different spectral characteristics, where in the right side region, 12 lines appeared with a maximum peak power of 176.58 nW, while the left side region exhibited 18 lines with a maximum peak power of 138.601 nW. The statistical properties in terms of mean, variance, and standard deviation power that are 65.76 nW, 3.746 pW 2 , 61.21 nW, respectively, under applied mechanical force 0.981 N.Spectrum slicing with 30 optical lines suitable for dense wavelength division multiplexing (SS-DWDM), with an improved power Budget was obtained using mechanical forces, leading to enhancing the OSNR. and also system high compactness.
Abstract The rapid growth of cloud-based data services and optical communication environments has increased concerns related to security, privacy, and trust in large-scale data processing systems. Traditional security approaches are often unable to handle advanced cyberattacks, insider threats, and data breaches, creating the need for intelligent and adaptive solutions. This paper proposes an AI-agent-enabled secure optical cloud ETL (Extract–Transform–Load) architecture for privacy-preserving and attack-resilient data transactions. The framework integrates optical data transmission with cloud-based ETL processing, where an autonomous AI agent continuously monitors the optical-cloud pipeline. The AI agent performs real-time anomaly detection, intrusion identification, user behaviour analysis, and threat prediction using historical and streaming data. Security is enhanced through zero-trust authentication, dynamic policy updates, identity and access management, and multi-level encryption during data extraction, transformation, optical transmission, and cloud storage. Experimental results demonstrate high attack detection accuracy with low processing overhead. Performance analysis shows that the Transformer model achieves the highest throughput of 106,383-transactions/sec and the lowest latency of 47.00 ms, outperforming conventional methods. The proposed framework provides a scalable and resilient solution for secure optical cloud ETL operations.
Abstract Optical millimeter-wave (MMW) generation is one of the key technologies of advanced optical communications systems of the next generation, such as 6G. Photonic based MMW generation with optical frequency multiplication has a number of advantages, which include low loss, wide tunability and easy integration with fiber-optics networks. Nevertheless, this is difficult to realize high multiplication factors with a high output power and harmonic purity. We present a 32-tupling optical MMW generation system based on cascaded dual-parallel Mach-Zehnder modulators (DPMZMs) that are optimized with the help of differential evolution (DE). DE algorithm uses five parameters including RF amplitude (VRF), phase shifts (φ 1 , φ 2 ), optical gain and electrical gain to maximize the 32× harmonic power at 160 GHz. It has a 5 GHz RF input and a 160 GHz MMW output with 0 dBm output that is 15.8 dB higher than the baseline with a signal-to-noise ratio of 70 dB. The optimized values are V RF = 23.09 V, φ 1 = 44.7deg, φ 2 = 97.4deg (of the DPMZMs), optical gain = 43.0 dB and electrical gain = 26.0 dB. It produces 12 usable harmonics between 10 GHz and 240 GHz. DE-optimised architecture provides a photonic MMW generation based on filterless solution with high performance.
Abstract This research introduces a new hybrid design for the Fiber-to-the-Home network architecture to serve 32 users with data rate up to 25 Gb/s per user. This new design combines Polarization Division Multiplexing, Wavelength Division Multiplexing, Spectral Amplitude Coding Optical Code Division Multiple Access, and Time Division Multiplexing to maximize spectral efficiency and system capacity. The SAC-OCDMA component utilizes the Identity Column Shift Matrix code, which leads to zero cross-correlation to eliminate multiple access interference. This system simulated using OptiSystem 23 software over a 60 km optical fiber link and the results shows the best Q -factor of 9.0308 with a bit error rate of 7.46 × 10 −20 , while the worst case across all of the 32 users maintains a Q -factor of 6.6734 with bit error rate of 8.761 × 10 −12 , both exceeding the ITU-T recommended threshold for reliable and acceptable communication.
Abstract UOWC provides high data rate transfers, but due to multiple users being in close proximity, performance suffers from beam overlap, crosstalk induced by dispersion, turbulence and congestion at access points. The authors propose a proactive method of managing interference as dynamic graphs and controlling interference through joint optimization of wavelength, beam divergence, transmission power and access point association. The authors name their proposed method Physics-Informed Graph Attention with Adaptive Beam and Color control (PIGAT-ABC). The authors incorporate channel characteristics into a graph-attention model which predicts interference patterns and will provide interference information to an optimization process that spans layers (cross-layer). The authors use a physics-based loss function to limit predicted signal-to-interference-plus-noise ratios (SINR) within realistic limits for the three types of water (clear, coastal, turbid) found in oceanic and coastal systems. The authors create a reproducible Monte Carlo simulation model using an analytical model develop to test the performance of their proposed solution. The authors show an improved performance over a baseline with fixed resources in a dense network (8 users with 20 dB SNR) whereby the proposed system outperformed the benchmark by 23.1 % reduction in Bit Error Rate (BER) and 31.3 % increase in spectral efficiency. The authors also demonstrate improved fairness and energy efficiency, and in support of a network centric method of avoiding interference.
Abstract Erbium-doped fiber amplifier (EDFA) has become a cornerstone in modern optical communication systems especially with C-band (1,530–1,665 nm), however, the demand of high optical capacity makes it necessary to extend the use of EDFA to L-band and U-band. In this paper, an EDFA has been designed and stimulated to be used with ultra-wide band applications, utilizing series and parallel-configurations. The proposed systems are simulated, and the performance analysis is conducted using Optisystem 15.0 software. The results show that both configurations presented ultra-wide flatness gain bandwidth. The series-configuration achieves superior gain flatness of 160 nm from 1,530 to 1,690 nm, with a gain ripple of 0.95 dB, and a maximum gain of 45.35 dB at 1,570 nm. While, the parallel-EDFA demonstrated an ultra-bandwidth with flexible gain control by adjusting the splitter coupling ratio. The optimum results were obtained at 0.1 coupling ratio with a total pump power of 540 mW. A flat gain for a wide range, 1,530–1,690 nm, and ripples of 5 dB are recorded. These results highlight the trade-off between the two architectures and demonstrate their potential to meet the growing demands of 5G/6G, IOT, and AI on optical communication systems infrastructure.
Abstract This paper has highlighted the simulative study and performance evaluation signature of single mode graded index doped fibers based high channel capacity with high speed vertical cavity surface emitting light source for long haul outdoor applications. The signal power attenuation is demonstrated through silica doped fibers against various modulation techniques based on different germanium dopant ratio with various silica doped fiber link lengths. Also the signal fiber dispersion coefficient is measured versus silica doped fiber length at different germanium dopant levels in the presence of various modulation techniques. As well as the overall optical system gain is clarified against Raman pumping power levels and number of Raman pumps at 20 % germanium dopant level in the presence of amplitude shift keying (ASK), frequency shift keying (FSK) and phase shift keying (PSK) modulation technique. Overall signal per noise ratio and overall system bit error rate (BER) are measured effectively against Raman pumping power levels with five and 10 Raman pumps at 20 % germanium dopant level in the presence of ASK optimum modulation technique.
Abstract As multiband elastic optical networks (MB-EONs) evolve, managing spectrum resources efficiently becomes fundamental to meeting growing traffic demands, where heterogeneous bandwidth demands must be provisioned across the C, L, S, and E spectral bands. Existing multiband provisioning approaches typically adopt fixed spectrum allocation sequences, which limit adaptability under varying traffic patterns and network conditions. To address this, we propose three adaptive spectrum allocation strategies: Bit Rate–Aware Spectrum Allocation Sequence (BR-SAS), Path Length–Aware Spectrum Allocation Sequence (PL-SAS), and a joint BR + PL-SAS method. These algorithms dynamically select between the C → L → S → E and E → S → L → C allocation sequences based on the bit rate and path length of incoming requests. Extensive simulations on the NSFNET and USNET topologies evaluate the proposed strategies in terms of request blocking probability (RBP), fairness, and band-sequence utilization behavior. Results show that among all three proposed algorithms, BR + PL-SAS achieves the lowest RBP across both topologies, and BR-SAS provides moderate performance in both RBP and fairness. In contrast, PL-SAS yields the highest fairness due to its balanced band utilization but exhibits the highest RBP, indicating reduced provisioning efficiency. Overall, the proposed BR + PL-SAS algorithm emerges as the most effective solution, outperforming single-parameter strategies and demonstrating the benefits of jointly considering bit rate and path length characteristics in multiband spectrum allocation.
Abstract In this paper, a half-adder (H-A) device is presented that utilizes non-linear material with 2-D photonic crystal waveguides (PhCWG). According to the beam interference principle, the construction uses air as its foundation and Y-shaped silicon (Si) rods in square lattice. A set of 25 × 19 Si rods with a radius ( r ) of 0.12 µm and a lattice constant ( a ) of 0.6 µm make up the structure’s square lattice. The structure works expertly by changing the phase of shaft of light with wavelengths of 1,550 nm, and it is numerically stimulated and confirmed using the finite-difference-time-domain (FDTD) technique. The design provides a contrast ratio (CR) of 5.806 dB, a transmission efficiency (TE) of 100 %, a response time ( R T ) of 23.62 fs for sum, and a low insertion loss ( I L ) of 0.96 dB for carry, all of which are significantly better and more efficient than those of other devices when the refractive index (RI), lattice constant and Si rod radius are optimized.
Abstract Lasers operating at 2 µm are highly useful for applications such as medical surgery, light detection and ranging (LIDAR), free-space communication, and directed infrared countermeasures (DIRCM). In this paper, the formation of a 2 µm region thulium-doped fiber laser is presented along with its performance evaluation using different pump wavelengths. A cost-effective thulium-doped laser in the 2 µm region is achieved by employing pump lasers of wavelengths 1,050 nm, 1,560 nm, 1,700 nm, and 1,740 nm. The input pump power is varied from 0.2 W to 2 W to analyze the output characteristics at 1,940 nm. The results show that output power increases with input pump power for all pumping schemes. A comparative study reported that a pump wavelength of 1,740 nm yielded the highest output power among the other cases. Therefore, it is observed that an efficient and stable 2 µm laser can be obtained using an optimised pump wavelength with suitable system parameters.
Abstract The development of 5G, 6G communication demands enhanced security and high-power long-haul optical networks to achieve efficient bandwidth utilisation, along with maintaining an acceptable quality factor (Q-factor) and bit-error rate (BER) for long-distance transmission. This paper evaluates a dense wavelength division multiplexing (DWDM) system that incorporates contemporary technology for long-haul communication. This paper presents the simulated design of two models on OptiSystem employing cubic root chirped-fibre Bragg gratings (CR-CFBG) with EDFA fibre in terms of performance metrics and scalability. Model I was tested across transmission distances of 120 km, 240 km, and 360 km with the NRZ and RZ. The proposed system achieves high Q-factors of 7.84, with a consistent BER of 1.47 × 10 −15 over 360 km as required. Model II was also tested across transmission distances up to 1,000 km (for the metro network) using NRZ. We achieved a favourable Q-factor of 6.34 and a BER of 1.05 × 10 −10 over 1,000 km. The transmission uses C+L band wavelengths (1,500–1,600 nm), and CR-CFBG works on the grating group-delay slope to trim the residual. The proposed CR-CFBG assisted DWDM system with EDFA demonstrates superior transmission performance by effectively compensating chromatic dispersion and enhancing signal amplification over long-haul links.
Abstract A radio frequency (RF) signal, when transmitted through an optical fiber network after modulating the light signal with the RF signal, is known as radio over fiber or RoF. This technology can utilize a large bandwidth so that it can support more users compared to regular wireless technology. RoF is a cost-effective and flexible alternative to fulfill the high and rapidly increasing consumer and commercial demands, such as internet services, which need bandwidth. In this paper, a hybrid 10 GHz RoF system is designed, which operates at multiple data rates of 5, 10, 15, and 20 Gbps. In this system, RF signal is used to modulate the light signal using a single-drive Mach–Zehnder modulator. The signal is transmitted through fiber, and coherent detection is implemented using a mixer and a local oscillator. Performance of the system is analyzed in terms of Q-factor, BER, and SNR. At 5 and 10 Gbps, system exhibits excellent performance, and at 20 Gbps, system performs moderately, while a significant degradation is observed at 15 Gbps due to spectral overlap and filtering limitations. This paper highlights the effect of bandwidth alignment and RF–data rate interaction in RoF systems.
