Optical Fiber Communication Systems Research Articles

Implementasi dan Pengaruh Time Division Multiplexing (TDM) terhadap Kualitas Transmisi Sinyal

Time Division Multiplexing (TDM) is a multiplexing technique that enables the transmission of multiple signals over a single communication channel by allocating separate time slots for each signal stream. This study aims to analyze the working principles of TDM, examples of its implementation, as well as the benefits and drawbacks of TDM in communication networks. The findings show that TDM can enhance data transmission efficiency through flexible bandwidth allocation, minimizing signal interference and thereby improving signal quality. Due to these advantages, TDM is widely used in fiber optic communication systems, such as telephone and internet networks. Additionally, all data processing is conducted within integrated circuits utilizing Plastic Optical Fiber (POF), allowing TDM to be implemented at a low cost.

Performance comparison of different intensity modulation formats for FSO systems

Abstract 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.

Coherent all Optical Reservoir Computing for Equalization of Impairments in Coherent Fiber Optic Communication Systems

Coherent all Optical Reservoir Computing for Equalization of Impairments in Coherent Fiber Optic Communication Systems

Improving the Performance of Bidirectional Communication System Using Second-Order Raman Amplifiers

In order to achieve low-cost scalability, the same-wavelength bidirectional (SWB) fiber communication system is a better solution. We present a detailed investigation of the performance of the different orders Raman amplifiers in same-wavelength bidirectional fiber communication systems. We discuss how to suppress the main factor affecting system performance which is Rayleigh scattering noise (RSN). By using different Raman amplifiers to construct different quasi-lossless transmission, the performance changes in the same-wavelength bidirectional fiber optic communication system were studied. On this basis, multi-channel and same-wavelength single fiber bidirectional system experiments were conducted to compare the performance of second-order Raman systems and first-order Raman systems. The results indicate that the Rayleigh scattering suppression effect of second-order Raman systems is better, and compared to first-order Raman systems, the average signal-to-noise ratio (SNR) can be increased by 2.88 dB.

Method for Controlling Dispersion in Order to Maintain a Quasi-Soliton Pulse Propagation Mode in High-Speed Fiber-Optic Communications System

Relevance: Every year, there is an increasing need to enhance the bandwidth and range of fiber-optic communication systems. The study of methods to control dispersion is relevant and helps maintain a quasi-soliton regime, which is essential for ensuring high-speed, reliable data transmission. Conducted modeling and calculations make this research practical and applicable. This will enable engineers to accurately predict the system's behavior and optimize its performance before implementing it in real-world networks.Problem statement: Investigation of the processes of maintaining a quasi-soliton regime in fibers with decreasing chromatic dispersion and alternating fibers with different signs of chromatic dispersion, both with and without initial chirping.Goal of the work: The development and analysis of techniques to control dispersion in order to maintain a quasi-soliton mode of light propagation in single-mode optical fibers.Methods: The study of the processes of maintaining a quasi-soliton regime was carried out by mathematical and numerical modeling. To substantiate the methods, theoretical analysis and calculations were carried out and schemes for a quasi-soliton fiber-optic communication system were developed and modeling was carried out.Result: The analysis of the results demonstrated the effectiveness of the proposed method and showed the efficiency and stability of the solutions in conditions that were close to real-world scenarios. Novelty: Models for maintaining a quasi-soliton regime and methods for studying them have been developed. The most effective ways to preserve quasi-soliton pulses over long distances have been analyzed.Practical significance: The developed models and research methods can be applied in the educational process and the development of real fiber-optic communication systems.

Deep Integration of Fiber-Optic Communication and Sensing Systems Using Forward-Transmission Distributed Vibration Sensing and on-off Keying.

The deep integration of communication and sensing technology in fiber-optic systems has been highly sought after in recent years, with the aim of rapid and cost-effective large-scale upgrading of existing communication cables in order to monitor ocean activities. As a proof-of-concept demonstration, a high-degree of compatibility was shown between forward-transmission distributed fiber-optic vibration sensing and an on-off keying (OOK)-based communication system. This type of deep integration allows distributed sensing to utilize the optical fiber communication cable, wavelength channel, optical signal and demodulation receiver. The addition of distributed sensing functionality does not have an impact on the communication performance, as sensing involves no hardware changes and does not occupy any bandwidth; instead, it non-intrusively analyzes inherent vibration-induced noise in the data transmitted. Likewise, the transmission of communication data does not affect the sensing performance. For data transmission, 150 Mb/s was demonstrated with a BER of 2.8 × 10-7 and a QdB of 14.1. For vibration sensing, the forward-transmission method offers distance, time, frequency, intensity and phase-resolved monitoring. The limit of detection (LoD) is 8.3 pε/Hz1/2 at 1 kHz. The single-span sensing distance is 101.3 km (no optical amplification), with a spatial resolution of 0.08 m, and positioning accuracy can be as low as 10.1 m. No data averaging was performed during signal processing. The vibration frequency range tested is 10-1000 Hz.

Application Of High Bandwidth Two-Stage Amplifier in Communication System

With the rapid development of communication technology, the application of high-bandwidth amplifiers in communication systems becomes more and more important. Currently researchers have applied high bandwidth two-stage amplifier technology in many fields such as cloud computing and data centers, video and audio transmission, virtual reality and augmented reality, Internet of Things, financial transactions, etc., and in this paper we will focus on its application in communication systems. In this paper, the basic principle and structure of two-stage amplifier are firstly described, and then the key theories of high-bandwidth technology including its concept, importance, principle and core technology of high-bandwidth design technology as well as stability analysis and design are elaborated, and the applications of high-bandwidth two-stage amplifiers in wireless communication system, fiber optic communication system, data center network, and satellite communication are enumerated. In summary, high-bandwidth two-stage amplifiers play a key role in a variety of communication systems, helping to provide stable, high-speed, long-range signal transmission. Through the research of this thesis, it is expected to provide new references and ideas for the research and development in the field of communication technology, and to promote the progress and innovation of communication system.

Low complexity and finer granularity quantization scheme for perturbation-based fiber nonlinearity compensation in coherent optical communication systems

In the efficient implementation of perturbation theory-based nonlinearity compensation method for reliable fiber-optic coherent communication systems, different quantization schemes have been proposed to reduce the required computational and implementation complexity. For example, the k-means clustering algorithm focused on reducing the number of perturbation coefficients to alleviate the burden of calculating the perturbation terms. In this paper, from the bit-level architectures of multipliers, we propose a multi-segment mixed-word-length quantization scheme that assigns different word lengths for the quantized perturbative coefficients to save computational resources, where Bayesian optimization is employed to derive the optimal hyperparameters involved in this scheme. The proposed scheme was evaluated by numerical simulations of single-channel and multi-channel optical fiber communication systems with dual-polarization 16-QAM modulation. The comprehensive numerical simulation results show that our proposed scheme demonstrates a complexity reduction of more than 65% without performance degradation compared with the traditional uniform quantization method with fixed-word-length, and was robust to the fiber length and baud-rate. We also carried out an experiment of single-carrier transmission over 18 × 100 km standard single-mode fiber with 20 Gbaud single-polarization 16-QAM signal. Similar to the numerical results, the hardware complexity can be reduced by 70.7% with negligible performance deterioration over the uniform quantization scheme. The proposed scheme shows great potential in real-world applications.

Dynamic interplay: unveiling inelastic breather collisions and modulation instability enhancement in a periodically gained inhomogeneous fiber optic communication system across temporal frequencies

Examining the impact of inhomogeneity on the propagation of femtosecond ultrafast optical pulses in fiber, we delve into the realm of the modified Hirota nonlinear Schrödinger equation (NLS) with inhomogeneity of variable coefficients (MIH-vc). Employing the Hirota bilinear method, we derive two soliton solutions for the modified Hirota NLS equation and analyze the effect of variable coefficients. The dynamical properties of these soliton solutions come to light as we meticulously analyze the corresponding plots. In our exploration, a noteworthy revelation unfolds as we witness the inelastic collision between two breathers, unleashing profound changes in the trajectory of femtosecond pulses. Furthermore, we showcase a detailed modulation instability analysis, unraveling the gain spectrum for our theoretical model. Through graphical illustrations, we elucidate how inhomogeneous functions intricately shape the modulation instability (MI) gain spectrum. A groundbreaking observation surfaces as, for the first time, we discern the periodic gain enhancement in relation to Group Velocity Dispersion along the fiber and its dynamic interactions.

The amplification effect of four-phonon scattering in CdX (X=Se, Te): The role of mid-frequency phonons

Recently, CdX (X = Se, Te) materials have garnered notable interest owing to their great application potential for high-efficiency solar cells, fiber optic communication systems, and nanoelectronic devices. The performance of optoelectric devices is significantly influenced by the thermal conductivity. In this study, a combination of machine-learning methods and first-principles calculations is utilized to investigate the phonon thermal transport properties of CdSe and CdTe, as well as to give deep insights into the phonon behavior in heat transfer. It is found that acoustic phonons dominate the lattice thermal conductivity (κ) in CdSe, while optical phonons contribute around 50 % to the κ value in CdTe. There are strikingly strong four-phonon scattering phenomena in both materials, which result in 55 % and 66 % reduction in κ values for CdSe and CdTe, respectively. Further analysis shows that the mid-frequency phonons play an important role in amplifying the four-phonon scattering. Its special frequency positions permit an unusually large number of four-phonon scattering processes to occur and cause large scattering of low-frequency phonons. This mechanism differs from earlier proposed features regarding large acoustic-optical gaps, bunching of acoustic branches and four-phonon Fermi resonance, which implies strong four-phonon anharmonicity. Thus, the present work opens up new prospects in the exploration and design of innovative thermoelectric material, which provides a more thorough understanding of the four-phonon scattering mechanisms in crystalline solids.

Switchable emissions of an Erbium-doped fiber laser using cascaded MZIs based on CHCF

In this work, a single and dual-wavelength erbium-doped fiber laser (EDFL) based on two Mach-Zehnder interferometers (MZIs) in cascade structure was experimentally validated. MZIs were assembled by joining a capillary hollow-core fiber (CHCF) piece between two multimode fibers (MMFs) sections. The switchable operation is reached by moving the spectrum of one MZI when the temperature is increased. The maximum measured signal noise to ratio (SNR) was more than 50 dB for the single and dual-wavelength laser lines. Besides, stable output is shown since no power and wavelength variations were noticed. It is important to mention that emissions are obtained at precise wavelength positions and not arbitrarily as described by other investigations. This EDFL can be used in applications of optical fiber communications systems and fiber sensing.

Experimental evaluation of wearable LED strip and side-emitting fiber for optical camera communications systems.

This paper presents an experimental evaluation of two types of light-emitting diode (LED)-based distributed transmitters, namely an LED strip and an LED-coupled side-emitting optical fiber, in both laboratory and wearable optical camera communication (OCC) systems. We study the system performance in terms of success of reception (SoR) with regard to the transmission distance. The best value of SoR is achieved when the camera is facing directly to the transmitter (Tx) from a close distance of 1 m. Additionally, we compare the power consumption, the signal-to-noise ratio performance (SNR) and all the obtained values under optimal conditions are better than the forward error correction (FEC) limit in OCC systems.

Design and implementation of a physical layer optical fiber security communication system based on a ZUC stream cipher

In this work, we have proposed a new physical layer encryption scheme to improve the security of optical fiber communication systems. The secrecy scheme is based on disturbance of the data cluster under the ZUC algorithm (named for Zu Chongzhi, a famous mathematician in ancient China), which is generated by optical XOR using a dual-drive Mach–Zehnder modulator (DD-MZM). A base scrambling pseudo random binary sequence (PRBS) generated by the ZUC stream cipher is introduced, which results in a better scrambling effect and randomness in the key stream of the block encryption structure. A simulation setup conducted in an encrypted transmission of the 64×64 grayscale image over 80 km of optical fiber shows that the authorized user can successfully decrypt the received signal, while the eavesdroppers cannot derive useful information with a bit error rate (BER) at approximately 0.5. In the simulation, after setting the delay compensation to 3.125 ps, a correct signal with a Q-factor as high as 11.3642 and a BER as low as 3.14295−30 can be obtained.

A fiber-wireless integration approach in WDM-PON architecture, boosted with polarization multiplexing and optical frequency comb source

Abstract The paper discusses an optical frequency comb source (OMCG)-enabled hybrid single mode fiber (SMF) and free space optical (FSO) communication system (fiber-wireless) delivering a total capacity of 96 Gbps by incorporating polarization division multiplexing (PDM) in passive optical network (PON) architecture. For the accomplishment of PDM, three diverse states of polarization (SOPs) are explored such as 00, 450, and 900. Performance investigation of proposed system is conducted for assessing Q factor and BER by exploring the different modulation formats in proposed system such as modified duo-binary return to zero (MDRZ), return to zero (RZ), compressed spectrum RZ (CSRZ), and non-RZ (NRZ). Results revealed that presented design can cover 30 km SMF + 3.4 km FSO range by incorporating MDRZ due to its spectral efficient and dispersion tolerant properties.

Dual-Core Photonic Crystal Fiber Polarization Beam Splitter Based on a Nematic Liquid Crystal with an Ultra-Short Length and Ultra-Wide Bandwidth

This paper presents a novel pentagonal structure dual-core photonic crystal fiber polarizing beam splitter (PS-DC-PCF PBS) filled with a nematic liquid crystal (NLC) in the central hole. Unlike previous designs with symmetric arrangements, the upper and lower halves of the structure have different air hole arrangements. The upper half consists of air holes arranged in a regular quadrilateral pattern, while the lower half features a regular hexagonal arrangement of air holes. By filling the central hole with birefringent liquid crystal, the birefringence of the structure is enhanced, reducing the coupling lengths along the x polarization and y polarization directions. The polarization properties, coupling characteristics, and the influence of different structural parameters on the extinction ratio of the polarizing beam splitter are analyzed using the full-vector finite element method. Simulation results demonstrate that the designed PS-DC-PCF PBS achieves a maximum extinction ratio (ER) of 72.94 dB with a splitting length of only 61.9 μm and a wide operating bandwidth of 423 nm (1.324–1.747 μm), covering most of the O, E, S, C, L, and U communication bands. It exhibits not only ultra-short splitting lengths and ultra-wide splitting bandwidth but also good manufacturing tolerances and anti-interference capabilities. The designed PS-DC-PCF PBS could provide crucial device support for future all-optical communication systems and has potential applications in fiber optic communication or fiber laser systems.

High-Capacity Coherent WDM Networks Empowered by Probabilistic Shaping and End-to-End Deep Learning

To optimize the functionality of coherent optical fiber communication (OFC) systems and enhance their capacity related to long-haul transmissions, wavelength-division multiplexing (WDM) and probabilistic constellation shaping (PCS) techniques have been used. This paper develops an end-to-end (E2E) deep learning (DL)-based PCS algorithm, i.e., autoencoder (AE) for a high-order modulation format WDM system that minimizes nonlinear effects while ensuring high capacity and considers system parameters, in particular those related to the OFC channel. Only the AE of the central channel is trained to meet the specified performance objective, as the system design employs identical AEs in each WDM channel. The simulation results show that the architecture should consist of two hidden layers, with thirty two nodes per hidden layer and a ”32×modulation order” batch size to obtain optimal system performance, when designing AE using a dense layer neural network. The behavior of the AE is examined to determine the optimum launch-power ranges that enhance the system's performance. The developed AE-based PCS-WDM provides a 0.4 shaping gain and outperforms conventional solutions.

The Digital Twin Framework for the Physical Wideband and Long‐Haul Optical Fiber Communication Systems

AbstractDigital twin (DT) modeling is essential to optical fiber communication systems, particularly for enhancing system performance, controlling the system in real time, and understanding signal nonlinearity. Conventional split‐step Fourier method ‐based simulations, however, struggle with wide‐band transmissions, plagued by increasing complexity and inherent biases due to inconsistent link parameter availability. Addressing these challenges, a hybrid data‐driven and model‐driven DT approach for the wide‐band and long‐haul physical systems with various system effects is developed. The approach utilizes a neural network (NN) to capture fiber nonlinear features as well as biased perturbations as “lumped” stochastic noises while offloading the linear effects to modules described by physical models of link elements. The model, tested in a 30.5‐Tbps 1200 km fiber transmission link with 40 channels, achieves a mean Q factor error of less than 0.1 dB and a maximum runtime of 1.3 s for NN processing under various launch powers, transmission lengths, and optical signal‐to‐noise ratios. Furthermore, the study has implemented a nonlinear compensation algorithm on the DT model, yielding a consistent enhancement in experimental data. The accuracy and adaptability of the DT model underline its suitability for planning, design, and optimization within the physical optical fiber communication systems.

The impact of Brownian motion on the optical solutions of the stochastic ultra-short pulses mathematical model

The stochastic generalized nonlinear Schrödinger equation (SGNLSE) of third order in the Stratonovich sense is examined here. New elliptic, hyperbolic, trigonometric, and rational stochastic solutions are obtained using a modified mapping method. Because the GNLSE is extensively used in nonlinear optical phenomena, optical fiber communication systems, communication and heat pulse propagation in materials, the obtained solutions may be used to study a broad range of relevant physical phenomena. In order to interpret the effects of multiplicative noise, the dynamic performances of the various obtained solutions are displayed utilizing 3-D and 2-D graphs. We infer that multiplicative noise impacts and stabilizes the behavior of SGNLSE solutions.

Simulation of Bismuth on-doped Fibre Lasers in the 1250-1300 nm Band

Optical fiber transmission has become the predominant mode of transmission in modern communication systems. The extensive bandwidth potential of optical fiber makes it crucial for achieving high-capacity transmission. With the successful development of anhydrous peak fiber, the issue of harmonic absorption caused by OH molecules has been effectively resolved. This novel fiber establishes a low-loss window within the wavelength range from 1280 nm to 1625 nm, thereby providing enhanced transmission capacity for fiber optic communication systems. By increasing WDM density, which involves the simultaneous utilization of multiple light signals with different wavelengths in the fiber, higher transmission capacity can be achieved. This paper presents a comprehensive simulation study on bismuth-doped fiber lasers operating within the 1250-1300nm band. Specifically, this study investigates the numerical relationship between laser power, threshold power, and pump power. The simulation results demonstrate that a threshold power level of approximately 1.5W is required for laser generation; no laser emission occurs below this threshold. Once the pumping power surpasses this threshold value, laser operation commences and output power increases proportionally with further increments in pumping power.

Spatial and mode selective switch for orbital angular momentum mode division multiplexing.

In analogy to a wavelength selective switch in wavelength-division multiplexing (WDM) optical fiber communication systems, a spatial and optical mode selective switch (SMSS) would be an important component in future ultrahigh capacity optical fiber communication systems based on space and mode division multiplexing. In this work, a free-space SMSS for orbital angular momentum (OAM) mode-division multiplexing (MDM) is proposed and experimentally demonstrated. The SMSS consists of a separating part for transforming OAM modes to spatial modes and a recombining part for selecting and recombining the modes to any spatial channel. The SMSS is able to implement strictly non-blocking switching between a total of 36 SDM/MDM channels configured as four spatial channels each supporting nine OAM mode channels.