Optical Fiber Communication Networks Research Articles

Linear Anti-interference Algorithm for Digital Signal Transmission in Fiber Optic Communication Networks based on Link Analysis

In order to achieve accurate transmission of protection signals in fiber optic communication networks, it is necessary to perform channel balancing configuration of fiber optic communication networks and adaptive forwarding control processing of relay protection signals, the author proposes an accurate transmission method for relay protection signals in fiber optic communication networks based on time-varying multipath fading suppression and adaptive beamforming. The system analyzes the sources of wireless long-distance pain signal interference signals, introduces anti-interference technologies such as two-dimensional joint processing (STAP), provides anti-interference algorithms and related gain analysis, and conducts signal processing gain simulation using MATLAB. Based on the analysis of comprehensive simulation results, at a given symbol length, the signal bandwidth increases, and the processing gain infinitely approaches the given theoretical limit value, rather than increasing nonlinearly. The reason is that the channel is affected by noise, and the channel estimation value and signal conjugate multiplication produce a noise quadratic term. At this point, the estimated value of the coherent region channel is reduced by the influence of noise, and the signal-to-noise ratio loss caused by the noise quadratic term is reduced, so the processing gain increases. During the process of infinite increase in signal bandwidth, the input signal-to-noise power ratio of the receiver tends to decrease towards an infinite value, limited by the size of the coherent region. The channel estimation value increases under the influence of noise, and the noise quadratic term is the main factor affecting the output noise power. When the symbol length is greater than the coherent time, the smaller the maximum Doppler frequency shift and the larger the coherent detection area, the greater the processing gain.

Design and characteristics study of bend-resistant and low-crosstalk few-mode multi-core fiber

This study introduces a novel 9-core, 4-mode fiber characterized by its bend resistance and minimal crosstalk. Utilizing a hetero-core scheme, the cores are effectively isolated through trenches and air holes, significantly reducing inter-core crosstalk. The cores are strategically arranged in a square array to facilitate easier splicing. Through comprehensive simulation calculations, it is demonstrated that four LP modes can be consistently transmitted within the C+L band. The effective refractive index difference between adjacent modes exceeds 10−3, ensuring negligible intra-core crosstalk. Concurrently, the inter-core crosstalk of the LP02 mode is maintained below − 40 dB/100 km. The fiber's bending radius can be minimized to 60 mm without compromising performance, with the corresponding bending loss for the LP02 mode in the two outer cores measured at 1.6 × 10−5 dB/m and 3.95 × 10−6 dB/m, respectively. Each of the nine cores exhibits an effective mode area exceeding 95 µm2, and the fiber's relative core multiplexing factor at 1550 nm is 27.62. The proposed fiber's superior performance positions it as a promising solution for practical applications in optical fiber communication networks, potentially addressing the burgeoning capacity crisis in communication systems.

Low crosstalk 125 μm cladding heterogeneous six-core few-mode fiber with air-hole array and trench structure

In order to be compatible with the current optical fiber communication network, we propose a 125 μm diameter heterogeneous six-core two linear polarization modes fiber with air-hole array and trench (HAT) structure. The coupled power theory and finite element method (FEM) are used to investigate inter-core crosstalk (ICXT), bending loss, and other properties. The HAT structure can effectively suppress ICXT; and the maximum ICXT is less than −38 dB/100 km in C + L band. The effective refractive index difference (Δneff) between modes is greater than 3 × 10-3, inter-mode crosstalk (IMXT) can be ignored. The maximum intrinsic loss is 0.187 dB/km; relative core multiplicity factor reaches 32.21. The relative spatial efficiency is 18 times that of traditional single-mode fibers. This fiber can be produced by chemical vapor deposition and existing optical fiber manufacturing technology. The designed fiber can be directly connected to the communication network to reduce the cost of equipment renewal, and the communication capacity can be increased by 18 times.

Characteristics Analysis of Hybrid Optical Amplifier with Doped Fiber Variations for Fiber Optic Communications Network

Optical communication networks are vital in the digital era, but data transmission becomes weak the longer the distance traveled by light. Erbium-Doped Fiber Amplifier (EDFA) technology is commonly used as an optical amplifier, but it still produces a small gain, Q-factor, and a significant noise figure. This study characterized the Hybrid Optical Amplifier (HOA) combinations that contain EDFA with various doped fibers. The characterization was performed through Optisystem software simulation by observing and analyzing the gain, noise of figure, and Q-factor generated by each doped fiber variant. The results showed that the combination of Ytterbium-doped Fiber produced the most significant gain of 15.83 dB, less noise figure of 5,661 dB, and a relatively high Q-factor of 35,615 at 1,550 nm. It indicates that the HOA combination is suitable and ideal for long-distance transmission in fiber optic communication network applications.

Obliquely propagating optical wave patterns to the (2 + 1)-dimensional chiral nonlinear Schrödinger equation in the absence and presence of Atangana derivative

The study aims to explore obliquely propagating optical wave solutions to the (2 + 1)-dimensional chiral nonlinear Schrödinger (NLS) equation in both the absence and presence of the Atangana derivative. In order to convert the classical-order chiral nonlinear Schrödinger equation to an ordinary differential equation, a transformation associated with wave obliqueness is applied. Hereafter, the unified method is applied to the reduced equation. As outcomes, the dark, periodic singular with unequal wave length, periodic with equal wavelength, periodic, unsmooth periodic, singular periodic soliton solutions are received to the ordinary differential equation. Later, the acquired solutions are then put to the applied transformation associated with obliqueness. Moreover, the fractional-order chiral NLS equation is solved by using the spatiotemporal Atangana derivative with oblique wave transformation and the unified method. In terms of wave obliqueness, fractionality, and applied technique sense, all generated wave solutions are revealed to be novel. Along with their physical explanations, the impacts of obliqueness and fractionality on the solutions are graphically illustrated. It is exposed that as obliqueness and fractionality increase, the optical wave phenomena change. Additionally, it is discovered that the employed method can be used to obtain novel optical soliton features to the chiral nonlinear Schrödinger equation with or without fractional and obliqueness constraints. It can be assured that the utilized method is more powerful than the other methods. As a result, the method can be used in future research to explain the many physical phenomena that arise in optical fiber communication networks.

Data Perspectives in AI-Assisted Fiber-Optic Communication Networks

Machine learning (ML) is widely being regarded as a powerful technology to solve various complex problems in fiberoptic communication networks. Recently, ML algorithms have been considered for a variety of use-cases in optical networks ranging from the design of network devices to the compensation of transmission impairments to predicting network-wide traffic flow patterns. As ML techniques are inherently data driven, the availability of relevant data sets largely dictates the performance of developed ML models. Presently, majority of ML-aided methods in the literature rely either on synthetic data from certain simulation tools or exploit data from some simple laboratory setups. However, developing robust ML-based solutions for real fiber-optic networks demands assembling big data from various parts as well as across different layers and domains of the network. Unfortunately, there is currently a lack of understanding among the research community about various crucial data aspects in practical optical networks as well as key challenges faced. While there has been a plethora of works discussing numerous ML applications in fiber-optic communications and networking, to the best of our knowledge, there is presently no paper which particularly focuses on data perspectives. In this paper, we aim to shed light on various critical data factors by first describing the tools and technologies imperative for adequate network monitoring and data acquisition. We also elucidate different data types, their physical sources, and their applications. Several useful data handling and pre-processing techniques for efficient network data collection, storage, presentation, analysis, etc., are discussed. Major challenges in the generation, transmission, and sharing of the data are highlighted and some potential solutions to the outstanding problems are proposed, thus paving the way for seamless availability of pertinent data sets essential for realizing intelligent data-driven operations in future fiber-optic networks.

Encryption in phase space for classical coherent optical communications

Optical layer attacks on optical fiber communication networks are one of the weakest reinforced areas of the network, allowing attackers to overcome security software or firewalls when proper safeguards are not put into place. Encrypting data using a random phase mask is a simple yet effective way to bolster the data security at the physical layer. Since the interactions of the random phases used for such encryption heavily depend on system properties like data rate, modulation format, distance, degree of phase randomness, laser properties, etc., it is important to determine the optimum operating conditions for different scenarios. In this work, assuming that the transmitter and the receiver have a secret pre-shared key, we present a theoretical study of security in such a system through mutual information analysis. Next, we determine operating conditions which ensure security for 4-PSK, 16-PSK, and 128-QAM formats through numerical simulation. Moreover, we provide an experimental demonstration of the system using 16-QAM modulation. We then use numerical simulation to verify the efficacy of the encryption and study two preventative measures for different modulation formats which will prevent an eavesdropper from obtaining any data. The results demonstrate that the system is secure against a tapping attack if an attacker has no information of the phase modulator and pre-shared key.

Remote fault detection and location of power fiber optic cable based on a logistic regression model

Abstract The current fiber optic communication network presents the characteristics of network scale, complexity, and efficiency, and the use of traditional means for the maintenance of power fiber optic cable has been greatly limited. In this paper, based on the characteristics of simple structure, convenient construction, strong randomness, strong sequence autocorrelation, and good iterative performance of chaos theory in a logistic regression model, a logistic-based remote fault detection and location system for power fiber optic cables is proposed. The fault location test is carried out through with TMS200 series fiber optic cable automatic monitoring management system and GIS method. The fault location error of the logistic-based fault detection method is less than ±3m, that of the GIS method is less than ±10m, and that of the TMS200 series cable automatic monitoring and management system is less than ±15. The comparison shows that this paper’s fault detection and location system is more accurate and can help maintenance personnel have a faster and more comprehensive understanding of the line situation. Realize the rapid repair work of faults, which provides great help to maintain the fiber optic cable lines.

PAWS and POCO: NIR Astrophotonic Instruments for Astronomy

AbstractFor near‐infrared ground and space‐based astronomy, compact photonic devices can replace the large bulk optical components in spectrographs, frequency combs, beam combiners, and sky subtraction filters, thus saving cost, reducing volume, weight, and power requirements. Photonic integrated circuits (PICs), analogous to integrated circuits (IC) in electronics, are particularly powerful to address innovative miniaturized solutions. Here, we demonstrate two new instrument prototypes: the Potsdam Arrayed Waveguide Spectrograph (PAWS) built around an array waveguide grating (AWG) PIC and Hawaii2RG detector, and the Potsdam Comb (POCO), a frequency comb generated by nonlinear processes in a micro‐ring resonator photonic chip. PAWS is calibrated by the remotely located POCO via the fiber optic communication network of the Leibniz‐Institute for Astrophysics Potsdam (AIP). The vision of future astrophotonic solutions for instrumentation is pointing toward hybrid solutions of PIC and detector arrays that hold the promise to dramatically change the layout of telescope focal plane instrumentation.

Simulation design and analysis of re modulation structure based on optical network

With the development of information age, the optical fiber communication network has also been greatly developed, and a large number of optical fiber systems should be shipped. Wavelength division multiplexing technology has become the most important technology in optical communication, which has a strong practical significance. The aim of this paper is to design and analyze the digital optical communication system by using the optical system. Using the most suitable configuration, including the optical transmission system at 1310nm and 1550nm wavelength as input power, using single-mode and multi-mode fiber as transmission, using zeroing code and non-zeroing code for modulation and demodulation system to code information, so as to maximize the spectral efficiency of the whole system. There are three evaluation indexes, including signal output power, signal noise spectrum, and transmission rate of two kinds of optical fiber.

Perspectives of thin-film lithium niobate and electro-optic polymers for high-performance electro-optic modulation

We summarized the recent progress and perspectives of Pockels electro-optic materials thin-film lithium niobate (TFLN) and electro-optic polymer (EOP) for next-generation wide-bandwidth and low-power electro-optic modulation.

Robust timing and frequency joint synchronization method for QNSC-enabled security optical communications system based on CO-OFDM

The security of optical fiber communication network has been paid more and more attention, and Quantum Noise Stream Cipher (QNSC) can guarantee its physical layer security. However, the QNSC system realized with CO-OFDM technology is very susceptible to timing synchronization error and carrier frequency offset. Existing symbol timing and frequency synchronization algorithms based on preambles have problems of timing metric platform, interference of side lobes, and low timing and frequency synchronization accuracy especially in optical signal transmission scenario of high-order modulation and low SNR. Furthermore, the preamble is not encrypted, which can be easily identified by illegal receiver. In order to solve above problems, a robust timing and frequency joint synchronization algorithm is proposed. The algorithm is composed of the preamble interleaved by conjugate, negative and image sequences of original element sequence. The preamble conforms to the preamble structure of Schmidl, Minn and CNI by adding negative and conjugate operator at the specific interval of the preamble. The correspond timing metric method, i.e. combination of Schmidl, Minn and CNI timing metric strategies, can fully extract characteristics of the preamble, and then timing and frequency joint synchronization is accurately obtained. For timing synchronization, experiments in 10Gbit/s CO-OFDM based QNSC system have illustrated that proposed algorithm has better timing synchronization performance than baseline algorithms. The detection probability is augmented and timing offset mean is decreased than that of baseline algorithms especially at low SNR. The simulation illustrates that proposed algorithm has more accurate frequency offset (FO) estimation performance compared with the baseline algorithms even at low SNR. Furthermore, the simulation illustrates the security performance of CO-OFDM based QNSC system is improved by encrypting the preamble with secret key.

Heterogeneous silicon-on-lithium niobate electro-optic modulator for 100-Gbaud modulation

Integrated lithium niobate (LN) electro-optic (EO) modulators are emerging for applications in next-generation optical fiber communication networks. To date, LN crystal waveguides have led the technology for high-speed modulators. On the other hand, on-chip LN modulators are expected to realize scalable signaling devices with mature complementary metal–oxide–semiconductor technology. In this study, a silicon-loaded LN modulator on the insulator substrate featuring a small footprint, a low driving voltage, and high-speed EO modulation is designed and fabricated. No etching or patterning of the LN is required. The measured halfwave-voltage length product is 1.9 V cm with a static modulation extinction ratio of 17.9 dB. The fabricated LN modulator has a modulation bandwidth of 60 GHz and supports high-speed signaling at a data rate up to 200 Gbit/s.

Digital interference signal filtering on laser interface for optical fiber communication

INTRODUCTION: Fiber laser communication is a communication method that uses laser and fiber medium to realize data transmission and information output OBJECTIVES: In order to reduce the signal interference of optical fiber communication laser interface and ensure the communication quality of optical fiber network. A filtering method of optical fiber communication laser interface interference signal based on digital filtering technology is designed. METHODS: In this paper, the interface model of optical fiber communication network is firstly constructed, and the interface noise signal is input into the digital filter bank. The digital quadrature filtering method and the least square algorithm are used to separate the denoised signals to reduce the crosstalk between the signals in the channel. In this way, the crosstalk component in the signal can be filtered out, and a better filtering processing effect of the laser interface interference signal can be achieved. RESULTS: The results of peak signal-to-noise ratio are above 25, which effectively filters the interference signal in the signal, and retains the effective signal completely. The intelligibility of optical fiber communication network in signal communication is above 0.94, and the highest value is 0.986. The distortion degree are all below 0.025, and the minimum value is 0.004. The communication bit error rate are all below 0.001, which ensures the communication quality of the network. CONCLUSION: The experimental results show that the signal noise reduction effect of the proposed method is good, which provides a reliable basis for filtering and separating interference signals of optical fiber communication laser interface.

Fuzzy Logic System Assisted Sensing Resource Allocation for Optical Fiber Sensing and Communication Integrated Network.

With the development of information transmission, there is an increasing demand for state monitoring of fiber-optic communication networks to improve the security and self-healing ability of the network. Distributed optical fiber sensing is one of the most attractive methods because it can achieve real-time detection of the whole network without additional sensing heads. However, when the sensing network is introduced into the communication network, the failure probability should be efficiently suppressed with limited sensing resources. In this paper, the fuzzy logic system is used to evaluate the impact of different sensing resource allocation on optical cable network quality. The link failure probability and path failure probability under the condition of uniform and non-uniform sensing resource allocation are simulated and analyzed, respectively. As shown in the analysis results, the failure probability under non-uniform allocation is significantly lower than under uniform allocation. In this paper, we discussed and addressed the allocation of the optical fiber sensing and communication integrated (OFSCI) network with the limited sensing resource for the first time. The results are helpful to develop an allocation strategy for optical fiber sensing and a communication integrated network with a higher robustness.

Coordinated Planning of Power Grids in Information Parks considering the Time-Space Transfer Characteristics of Data Center Loads

With the development of green energy, the penetration rate of new energy in the power grid is rising rapidly. Incorporating a large amount of new energy into the power grid will affect the power supply balance of the power grid, and even in severe cases will affect the safe and stable operation of the power grid. The information park has various small and medium data centers. The adjustable load of the data center can be transferred in time and space through the optical fiber and other communication networks, which can enhance the controllability of the power grid to a certain extent and promote the consumption of new energy. This paper proposes a collaborative planning method for information parks that considers the temporal and spatial transfer characteristics of data center loads, builds a load transfer model for data centers and builds a park power grid expansion model with the goal of minimizing the total cost of construction and operation. In this paper, an example of a park is used to verify the calculation example, and it is compared with other schemes to verify the feasibility of the method in this paper.

E-Commerce Data Access Control and Encrypted Storage Based on Internet of Things

In order to discuss the access control and encrypted storage of Internet of Things data for e-commerce data, a method of Internet of Things data access control and encrypted storage based on optical fiber network communication is proposed. Build an IoT application model based on optical fiber network communication, which consists of a perception layer, a network layer, and an application layer. The network layer is through the optical fiber communication network. The information collected by the optical fiber sensor in the perception layer is transmitted to the application layer for processing. And the model-aware layer adopts the dynamic transformation encryption method for attribute decomposition, and the Internet of Things data access control strategy based on key management and implement IoT data access control and encrypted storage based on the IoT application model of optical fiber network communication. The experimental results show that when this method implements access control and encrypted storage of IoT data, it has the advantages of high efficiency, low storage space overhead, and low computational cost of fiber network nodes, and the security of the processed IoT data is as high as 97.77%. Conclusion. This method can effectively deal with the limited computing performance and storage performance of the perception layer nodes of the application model; larger and larger application requirements with a large number of nodes.

Techniques for applying reinforcement learning to routing and wavelength assignment problems in optical fiber communication networks

We propose a novel application of reinforcement learning (RL) with invalid action masking and a novel training methodology for routing and wavelength assignment (RWA) in fixed-grid optical networks and demonstrate the generalizability of the learned policy to a realistic traffic matrix unseen during training. Through the introduction of invalid action masking and a new training method, the applicability of RL to RWA in fixed-grid networks is extended from considering connection requests between nodes to servicing demands of a given bit rate, such that lightpaths can be used to service multiple demands subject to capacity constraints. We outline the additional challenges involved for this RWA problem, for which we found that standard RL had low performance compared to that of baseline heuristics, in comparison with the connection requests RWA problem considered in the literature. Thus, we propose invalid action masking and a novel training method to improve the efficacy of the RL agent. With invalid action masking, domain knowledge is embedded in the RL model to constrain the action space of the RL agent to lightpaths that can support the current request, reducing the size of the action space and thus increasing the efficacy of the agent. In the proposed training method, the RL model is trained on a simplified version of the problem and evaluated on the target RWA problem, increasing the efficacy of the agent compared with training directly on the target problem. RL with invalid action masking and this training method outperforms standard RL and three state-of-the-art heuristics, namely, k shortest path first fit, first-fit k shortest path, and k shortest path most utilized, consistently across uniform and nonuniform traffic in terms of the number of accepted transmission requests for two real-world core topologies, NSFNET and COST–239. The RWA runtime of the proposed RL model is comparable to that of these heuristic approaches, demonstrating the potential for real-world applicability. Moreover, we show that the RL agent trained on uniform traffic is able to generalize well to a realistic nonuniform traffic distribution not seen during training, thus outperforming the heuristics for this traffic. Visualization of the learned RWA policy reveals an RWA strategy that differs significantly from those of the heuristic baselines in terms of the distribution of services across channels and the distribution across links.

Modulation of Multichannel Electronic Communication Signal Parameters Based on a Nonlinear Phase Principle

In order to solve the difficulty of the optical fiber communication system and network as the infrastructure of the global communication network, which is faced with the requirement of large capacity and high speed, the author proposes a method to modulate the parameters of multichannel electronic communication signals based on the nonlinear phase principle. The method includes multichannel electronic communication signal search, multichannel electronic communication signal parameter modulation, and multichannel electronic communication signal automatic acquisition algorithm realization. Experimental results show that under the conditions that the sampling frequency is set to f = 8.145 MHz, the length of the C/A code period is set to 1 ms, and the 1 ms data packet contains 8145 sampling points, under the same experimental conditions, the capture probability of this experiment reaches 100% and the traditional algorithm has a capture probability of up to 70%. Modulation of multichannel electronic communication signal parameters based on nonlinear phase principle has a positive guiding role in building a high-speed optical fiber communication system and network with long distance, large capacity, high elasticity, high reliability, and low delay.

Theoretical analysis of measurement-device-independent quantum key distribution systems integrated into fiber-optic communication lines using dense wavelength division multiplexing

Subject of study. The effect of noise resulting from spontaneous Raman scattering, four-wave mixing, and linear channel crosstalk on the performance of measurement-device-independent quantum key distribution systems with symmetric and asymmetric realizations is studied. Mathematical models of the measurement-device-independent quantum key distribution system and considered channel noise sources are presented. The secure key generation rate was calculated in all cases for assessment and subsequent analysis of the system performance. These results enabled the identification and presentation of the operation features of the measurement-device-independent quantum key distribution system upon its integration into existing fiber-optic communication networks using dense wavelength division multiplexing. Aim of the work. The performance of measurement-device-independent quantum key distribution systems integrated into fiber-optic communication lines using dense wavelength division multiplexing by means of numerical simulation is investigated. Method. An approach based on analysis of the Raman scattering cross section plot and allocation of the information channels of frequencies corresponding to areas located sideways to the pump wavelength was used to determine the optimal configurations of the allocation of quantum and information channels. A single-photon scheme in one symmetric and two asymmetric system realizations was considered for numerical simulations of the quantum key distribution system with an untrusted node. A security analysis was performed according to the Devetak–Winter bound that enables estimating the secure key generation rate in an asymptotic mode (for symmetric infinite sequences) in the presence of collective attacks in the quantum channel. Main results. It was confirmed that the implementation of measurement-device-independent quantum key distribution systems with equal paths of the sender and the receiver (i.e., symmetric) is optimal. The result deteriorated with an increase in the asymmetry parameter. If the quantum channel is within the C-band, the advantage of the symmetric realization was minimal, and it was almost indiscernible when the number of information channels was increased to 40. However, if the quantum channel was at the wavelength of 1310 nm (O band), the difference was significant. Moreover, allocation of the wavelength of 1310 nm to the quantum channel enables the longest distance of operation, and it weakly depends on the number of channels. Practical significance. For practical implementation of quantum key distribution systems, their integration into existing telecommunication infrastructure is of particular interest. This can be achieved through the simultaneous propagation of quantum and information channels in the fiber-optic communication lines by means of multiplexing, and in particular, dense wavelength division multiplexing. However, the power levels characteristic for quantum signals are significantly lower than those for information signals. Therefore, if the information and quantum channels propagate in the same fiber, the noise from the information channels significantly reduces the performance of the quantum key distribution systems. For this reason, the physical and mathematical description, analysis, and numerical simulation of the noise and its interaction with different quantum key distribution systems aimed at identifying the most effective integration method are crucial for the integration of quantum key distribution systems into existing telecommunication networks.