Optical Fiber Communication Systems Research Articles

The intrinsic mode activation and evolution in fiber splicing based on 3D refractive index profile characterization

Fiber fusion splicing tremendously affects the modal stability, insertion loss and transmission quality of the optical fiber communication systems. Especially, in the few-mode fibers, a tiny dissatisfactory fiber splicing operation may lead to a big modal perturbation or unexpected mode coupling. In this paper, we propose a 3D refractive index profile visualization method to demonstrate the mode activation and evolution in fiber fusion splicing. A refractive index profile measuring instrument is established and applied to detect the 3D refractive index profile deformation caused by the fiber splicing. Then, based on the measured values of 3D refractive index profile, the mode activation is analyzed for fiber splicing between a single-mode fiber and a two-mode fiber with different core-offset distance. Results show that the mode begins to tremble with a core-offset of 4 μm and the high-order modes are effectively activated at the core-offset of 7 μm. The basic theoretical model and experiment results provide a profound support in almost all kinds of fiber splicing operation, mode interference construction and mode coupling modulation. Additionally, the method can be expanded to the research on fiber cleaving and bending.

Performance Analysis of Spectral Amplitude Coding Methods in Fiber Optical Communication System

Performance Analysis of Spectral Amplitude Coding Methods in Fiber Optical Communication System

Dual-Stage Double-Pass Extended L-Band Erbium-Doped Fiber Amplifier with Improved Gain Performance

Extended L-band erbium-doped fiber amplifiers (EDFAs) have attracted much attention in recent years despite their relatively low gain levels. In this paper, a dual-stage extended L-band EDFA with improved gain level is demonstrated by using an Er/Yb/P co-doped fiber-based double-pass structure assisted by a low noise pre-amplifier. High gain levels of up to 48.79 dB at 1566 nm and 20.05 dB at 1621.4 nm are achieved with saturated output power at 1605 nm of 20.58 dBm under a total pump power of only 400 mW. Bandwidths with the gain of more than 20 and 30 dB are reached up to 66 nm (1555.4–1621.4 nm) and 58.4 nm (1557.5–1615.9 nm), respectively. The noise figure benefited by using the low noise pre-amplifier is 5.40 ± 1.55 dB in the 1565–1610 nm range. The wide gain bandwidth, high gain level and relatively low pump power give it great potential for future high-capacity optical fiber communication systems.

Modelling and numerical analysis of combined dual impact of SRS and FWM on the performance of upstream and downstream channels of a novel UDWDM/DWDM-PON

Wavelength division multiplexing (WDM) is an important method in modern optical communication systems for both long-haul and access networks. Particularly, after being standardized by Telecommunication Standardization Sector of International Telecommunication Union (ITU-T), WDM passive optical network (WDM-PON) becomes a considerable choice for fronthaul implementations of 5G networks. Stimulated Raman scattering (SRS) and four-wave mixing (FWM) are crucial nonlinear impacts that significantly limit the performance of WDM-based optical fiber communication systems. In this paper, an ultra-dense/dense WDM-PON (UDWDM/DWDM-PON) architecture has been proposed and combined dual impact of SRS and FWM on performances of upstream channels (USCs) and downstream channels (DSCs) of the proposed UDWDM/DWDM-PON has been numerically analyzed. USCs have been assumed to operate in 1310 nm region while operating wavelength region of DSCs has been taken as 1550 nm. Simulations have been performed on both UDWDM-PON architectures with 3.125 GHz and 6.25 GHz channel spacings and DWDM-PON architectures with channel spacings between 12.5 GHz and 100 GHz. 2x15-channel and 2x63-channel system structures have been considered in simulations. Signal-to-crosstalk ratio (SXR) has been chosen as performance parameter and its variation with channel input powers, channel spacings and channel lengths have been simulated for both USCs and DSCs of 2x15- and 2x63-channel UDWDM/DWDM-PONs. Results show that the proposed UDWDM/DWDM-PONs using single G.652 fiber can exhibit a reliable communication with minimum 23 dB SXR performance under combined dual impact of SRS and FWM unless some highlights about input powers and channel lengths mentioned in the paper are neglected.

Optical Fiber Connector Technology

Various optical fiber connectors have been developed during the 40 years since optical fiber communications systems were first put into practical use. This paper describes the key technologies for optical connectors and recent technical issues.

Silicon-Organic Hybrid Electro-Optic Modulator and Microwave Photonics Signal Processing Applications.

Electro-optic modulator (EOM) is one of the key devices of high-speed optical fiber communication systems and ultra-wideband microwave photonic systems. Silicon-organic hybrid (SOH) integration platform combines the advantages of silicon photonics and organic materials, providing a high electro-optic effect and compact structure for photonic integrated devices. In this paper, we present an SOH-integrated EOM with comprehensive investigation of EOM structure design, silicon waveguide fabrication with Slot structure, on-chip poling of organic electro-optic material, and characterization of EO modulation response. The SOH-integrated EOM is measured with 3 dB bandwidth of over 50 GHz and half-wave voltage length product of 0.26 V·cm. Furthermore, we demonstrate a microwave photonics phase shifter by using the fabricated SOH-integrated dual parallel Mach-Zehnder modulator. The phase shift range of 410° is completed from 8 GHz to 26 GHz with a power consumption of less than 38 mW.

Compensating Chromatic Dispersion and Phase Noise using Parallel AFB-MBPS For FBMC-OQAM Optical Communication System

Filter Bank Multi-Carrier Offset-QAM (FBMC-OQAM) is one of the hottest topics in research for 5G multi-carrier methods because of its high efficiency in the spectrum, minimal leakage in the side lobes, zero cyclic prefix (CP), and multiphase filter design. Large-scale subcarrier configurations in optical fiber networks need the use of FBMC-OQAM. Chromatic dispersion is critical in optical fiber transmission because it causes different spectral waves (color beams) to travel at different rates. Laser phase noise, which arises when the phase of the laser output drifts with time, is a major barrier that lowers throughput in fiber-optic communication systems. This deterioration may be closely related among channels that share lasers in multichannel fiber-optic systems using methods like wavelength-division multiplexing with frequency combs or space-division multiplexing. In this research, we use parallel Analysis Filter Bank (AFB) equalizers in the receiver part of the FBMC OQAM Optical Communication system to compensate for chromatic dispersion (CD) and phase noise (PN). Following the equalization of CD compensation, the phase of the carriers in the received signal is tracked and compensated using Modified Blind Phase Search (MBPS). The CD and PN compensation techniques are simulated and analyzed numerically and graphically to determine their efficacy. To evaluate the FBMC's efficiency across various equalizers, 16-OQAM is taken into account. Bit Error Rate (BER), Optical Signal-to-Noise Ratio (OSNR), Q-Factor, and Mean Square Error (MSE) were the primary metrics we utilized to evaluate performance. Single-tap equalizer, multi-tap equalizer (N=3), ISDF equalizer with suggested Parallel Analysis Filter Banks (AFBs) (K=3), and MBPS were all set aside for comparison. When compared to other forms of Nonlinear compensation (NLC), the CD and PN tolerance attained by Parallel AFB equalization with MBPS is the greatest.

End-to-End Deep Learning of Joint Geometric Probabilistic Shaping Using a Channel-Sensitive Autoencoder

In this paper, we propose an innovative channel-sensitive autoencoder (CSAE)-aided end-to-end deep learning (E2EDL) technique for joint geometric probabilistic shaping. The pretrained conditional generative adversarial network (CGAN) is introduced in the CSAE which performs differentiable substitution of the optical fiber channel model under variable input optical power (IOP) levels. This enables the CSAE-aided E2EDL to design optimal joint geometric probabilistic shaping schemes for optical fiber communication systems at varying IOPs. The results of the proposed CSAE-aided E2EDL technique show that for a dual-polarization 64-Gbaud signal with a transmission distance of 5 × 80 km, when the modulation format is a 64-quadrature amplitude modulation (QAM) or a 128-QAM, the maximum generalized mutual information (GMI) level learned via CSAE-aided E2EDL is 5.9826 or 6.8384 bits/symbol under varying IOPs, respectively. In addition, the pretrained CGAN, as a substitution for optical fiber transmission model, accurately characterizes the distortion of signals with different IOPs, with an average bit error ratio (BER) difference of only 1.83%, an average mean square error (MSE) of 0.0041 and an average K-L divergence of 0.0046. In summary, this paper delivers new insights into the application of E2EDL and demonstrates the feasibility of joint geometric probabilistic shaping-based E2EDL for fiber optic communication systems with varying IOPs.

Research on Adaptive Reverse Design Method of Integrated Optical Fiber Communication System

The vigorous development of network technology promotes the progress of communication transmission technology, and the progress of communication transmission technology also drives the development of network technology. Optical fiber communication technology is widely used in communication industry because of its strong anti-interference ability, fast transmission speed and large amount of information. With the explosive growth of network data traffic in recent years, the transmission capacity of optical fiber communication has been continuously improved, coherent optical communication technology has developed rapidly, the trend of intelligence, grouping and broadband has become more and more obvious, and new photoelectric devices have been continuously developed and used. Optical fiber communication technology is undergoing tremendous changes and will become more important. In this paper, the application of optical fiber communication transmission technology is discussed in detail, and an adaptive reverse design method of integrated optical fiber communication system is proposed in order to promote the rapid development of optical fiber communication transmission technology.

Physical layer secure key generation and distribution based on noise variances in optical fiber communications systems

Considering the key demand in the secure optical fiber communication, a key generation and distribution scheme based on random noise variances is proposed. The noise of optical communication systems is inevitable due to the influence of various factors. The additive noise that cannot be eliminated is random after digital signal processing, which ensures the randomness of the key. However, the range of system noise variances is small and the noise of links is exposed. A random Gaussian white noise is added at receivers, which increases the noise fluctuation and enhances security. Legitimate parties obtain secure keys by calculating the data inconsistency rate, where the consistency comes from the correlation of noise variances in adjacent time slots over a period of time. Experimental results demonstrate that the error-free key is obtained with the key generation rate of 1.6 Mbit/s over 105 km standard single-mode fiber. Moreover, the security analysis shows that the proposed key generation and distribution scheme can resist fiber-tapping attacks.

Convolutional modulation spectra of soliton molecular complexes in ultrafast laser

Optical soliton molecules are common pulse states in dissipative system, and they can combine with each other to form soliton molecular complexes which exhibit cumbersome spectral characteristics. As there is an intrinsic connection between the spectra of the soliton molecules and soliton molecular complexes, we demonstrate that the spectra of soliton molecular complexes are the results of quadratic modulation between component solitons, through experimental verification and simulation analysis. Specifically, two strongly bound solitons modulate to form soliton molecules, and then the soliton molecules modulate with weakly bound soliton pairs to form soliton molecular complexes, which is called convolutional modulation. The results obtained have vital significance to better understanding of the intrinsic nature and interaction of the solitons. The formation of quadratic modulated spectra plays an inspiring role in the fields like modern fiber-optic communication systems, optical frequency combs and its related precision measurements and various practical applications.

Gain Maximization of BDFA between the Wavelength of 1700nm to 1800nm

Fiber optic communication technology is becoming increasingly important in various fields, and high-speed, large-capacity fiber optic transmission systems are urgently needed. The design of fiber amplifiers is influenced by both fiber length and doping concentration. Although the Erbium-doped fiber amplifier (EDFA) is one of the most widely used components in fiber optic communication systems, its working area cannot meet the growing demand for network traffic.This paper presents a new fiber amplifier operating in the spectral region of 1700-1800 nm, pumped by commercially available laser diodes, highlighting the potential benefits of developing optical amplifiers for new spectral regions.This paper constructs a model to optimize gain at the central wavelength by finding relevant parameters, fitting a binary function of gain as a function of doping concentration and fiber length using Matlab, and optimizing the maximum gain using a simulated annealing algorithm. The proposed fiber amplifier has potential applications in telecommunications, sensing, and spectroscopy. The design of the amplifier has been optimized to achieve high gain and low noise figures, which are crucial for practical applications. Furthermore, the amplifier can be easily integrated into existing fiber optic networks, making it a promising candidate for future optical communication systems.

Resonant collisions among X-type, multi-lump, generalized breathers, N-solitons and rogue waves in plasma

This paper studies the (1+1)-dimensional Kuramoto–Sivashinsky equation (1D-KSE) also known as canonical evolution equation within the context of flame front propagation, plasma instabilities, and phase turbulence in reaction–diffusion systems. We use Hirota’s derivatives to formulate bilinear equations and subsequently compute various types of solitons. We obtain lump solution, lump one strip, lump two strip, X-type, lump periodic solution, generalized breather and rogue wave solutions for our governing model with the help of Hirota bilinear method (HBM) and the ansatz approach. Breathers solutions may be used to improve the efficiency of fiber optic communication systems and solitons in plasma waves. Rogue wave solutions may be used for the safety of oil platforms and ships while lump wave solutions can be utilized in manipulating and controlling laser beams for materials processing or laser surgery. We also discuss one, two and other soliton interactions for 1D-KSE under some constraint conditions. These interactions may be discussed in plasma stability and confinement, which can control fusion as a future energy source.

Quantum and Quantum-Inspired Stereographic K Nearest-Neighbour Clustering.

Nearest-neighbour clustering is a simple yet powerful machine learning algorithm that finds natural application in the decoding of signals in classical optical-fibre communication systems. Quantum k-means clustering promises a speed-up over the classical k-means algorithm; however, it has been shown to not currently provide this speed-up for decoding optical-fibre signals due to the embedding of classical data, which introduces inaccuracies and slowdowns. Although still not achieving an exponential speed-up for NISQ implementations, this work proposes the generalised inverse stereographic projection as an improved embedding into the Bloch sphere for quantum distance estimation in k-nearest-neighbour clustering, which allows us to get closer to the classical performance. We also use the generalised inverse stereographic projection to develop an analogous classical clustering algorithm and benchmark its accuracy, runtime and convergence for decoding real-world experimental optical-fibre communication data. This proposed 'quantum-inspired' algorithm provides an improvement in both the accuracy and convergence rate with respect to the k-means algorithm. Hence, this work presents two main contributions. Firstly, we propose the general inverse stereographic projection into the Bloch sphere as a better embedding for quantum machine learning algorithms; here, we use the problem of clustering quadrature amplitude modulated optical-fibre signals as an example. Secondly, as a purely classical contribution inspired by the first contribution, we propose and benchmark the use of the general inverse stereographic projection and spherical centroid for clustering optical-fibre signals, showing that optimizing the radius yields a consistent improvement in accuracy and convergence rate.

Future trends in optical wireless communications systems: Review

Optical fibers are frequently used in data transmission systems, Because of their ability to transmit large amounts of information and dielectric nature. In central, metropolitan, or broad-area applications, network topologies incorporating many wavelengths per optical fiber are utilized to connect thousands of users with a wide variety of transmission rates and capacities. The simultaneous transmission of many wavelengths over a fiber with a nm range of 1300 to 1600 is a potent characteristic of an Optical communication network. Wavelength division multiplexing (WDM) is a method for combining various wavelengths onto a single fiber. The WDM concept, when combined with optical amplifiers, produces communication lines that enable quick communication between users across national borders. An overview of the difficulties with fiber-optic communication is provided in this paper. The areas that will be most important for the development of optical communications in the future are outlined in this study. Modern optical fibers and integrated optics were both developed in the dominion of optical machinery and parts. Optical fiber communication systems are widely used for high-speed data transmission over long distances. There are some specific details and examples of optical fiber communication systems such as Fiber Optic Cables, Light Sources, optical modulator, optical amplifier, optical receivers, fiber optical network, medical applications.

High-power, low noise, high gain few-mode fiber amplifier

The few-mode erbium-doped fiber amplifier (FM-EDFA) is a necessary component for high-capacity long-haul mode-division multiplexing (MDM) fiber optic communication systems. In this paper, an all-fiber few-mode amplifier based on erbium-ytterbium co-doped double-clad fiber is designed and demonstrated. We have developed a fiber-optic pump beam combiner and a few-mode isolator. Combined with the two-stage cascade method, an all-fiber few-mode fiber amplifier with high-power, high-gain and low-noise is realized. Simultaneous amplification of 6 modes (LP01, LP11a, LP11b LP21a, LP21b and LP02) are achieved in the 1535–1565 nm range with average modal gain greater than 40 dB, maximum saturated output power up to 29.5 dBm, differential modal gain (DMG) of ∼3 dB and minimum noise figure (NF) of 4.69 dB.

High-Speed Directly Modulated Widely Tunable Hybrid Square/Rhombus-Rectangular Coupled Cavity Lasers

We report the latest development in high-speed directly modulated tunable laser based on simple and compact hybrid square/rhombus-rectangular laser (HSRRL), aiming for low-cost deployment in next generation high-throughput optical interconnects, intra-/inter-data center networks, and optical fiber communication system. The HSRRL is composed of a deformed square whispering gallery mode (WGM) microcavity and a Fabry–Pérot (FP) cavity, and the WGM microcavity is used as an end face of the FP cavity with mode selection. A deformable WGM microcavity is designed to obtain a high reflectivity. The HSRRL, fabricated with deep-etching processing steps similar to FP laser without grating or epitaxial regrowth, has achieved 7-mA threshold current, 0.4-mW/mA slope efficiency, above 52-dB side mode suppression ratio (SMSR), and 16.2-GHz modulation bandwidth with injection currents of 34.3 mA and 60 mA for WGM microcavity and FP cavity, respectively. A wavelength tuning from 1537.40 nm to 1570.42 nm is realized by adjusting the injection currents simultaneously. In the tuning range, the laser has an SMSR greater than 40 dB, a linewidth less than 4 MHz, and a 3-dB modulation bandwidth greater than 14 GHz.

Systematic approach to connect density-matrix formalism and Stokes formalism for modal analysis in mode-division multiplexing optical-fiber communication systems

Systematic approach to connect density-matrix formalism and Stokes formalism for modal analysis in mode-division multiplexing optical-fiber communication systems

Trends of and Prospects for the Development of Fiber-Optic Communication Systems

Trends of and Prospects for the Development of Fiber-Optic Communication Systems

Fiber Optics: The Fundamentals, Types, Advantages and Applications

Abstract: This study's goal is to shed light on recent advancements and improvements in the use of optical fibre as a data transport. It offers a wealth of knowledge on the architectural design, upkeep, troubleshooting, and benefits of fibre optic transmission over copper or electrical transmission. Broadband networks all across the world depend on fibre optic lines as vital telecommunications infrastructure. Optical fibres are now the preferred transmission medium for long-distance and high data rate transmission in telecommunication networks because they offer large transmission bandwidth with hardly any latency. An overview of fibre optic communication systems is provided in this article, together with information on their architectures, important technologies and innovations, applications, types, testing, and troubleshooting.