Article
Engineering, Electrical & Electronic
Yu Chen, Mohammadamin Baniasadi, Majid Safari
Summary: This paper proposes an approximated channel model that describes the effect of noise and nonlinearity in a nonlinear frequency division multiplexed (NFDM) communication system. The optimal input distribution that maximizes the mutual information under a peak amplitude constraint is studied. It is found that geometrically shaped amplitude-constrained constellation designs can provide significant mutual information gains. However, further probabilistic shaping and constellation size optimization only offer limited additional gains. In the case of a matched filtered signaling system, a channel model neglecting the correlation between subcarriers is proposed, and it is shown that the geometric shaping of the input constellation can provide promising gains in mismatch capacity over the unfiltered scenario.
IEEE TRANSACTIONS ON COMMUNICATIONS
(2023)
Article
Optics
Shuangxi Zhang, Jianfei Liu, Xiangye Zeng, Jia Lu, Ying Wei, Ruiming Qi
Summary: A modified partitioned frequency domain equalization algorithm is proposed in this paper to address the slow convergence speed and poor equalization effect of digital equalizer in the polarization division multiplexed (PDM)-MDM system. Simulation results show that the modified algorithm can achieve significantly better SER performance and improve the convergence rate compared to the traditional algorithm.
Article
Engineering, Electrical & Electronic
Hao Guo, Ting Li, Fengping Yan, Guobin Ren, Wei Wang, Xiangdong Wang, Qi Qin, Guifang Wu, Jiao Gao, Baoyuan Wang, Haoyu Tan, Wenhua Ren, Ting Feng
Summary: This article reports the design and characterization of a six-mode erbium-doped fiber amplifier (6M-EDFA) for mode division multiplexing systems. The design utilizes a center-depressed optical fiber and adjustment of parameters to reduce splice loss. Through analysis and optimization, high gain and low differential modal gain are achieved. The performance of the designed amplifier is verified using a MDM transmission system.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Optics
TianJin Wen, Shecheng Gao, Wei Li, Jiajing Tu, Cheng Du, Ji Zhou, Zhaohuan Ao, Bin Zhang, Weiping Liu, Zhaohui Li
Summary: A ring-core erbium-doped fiber supporting up to the fourth-order orbital angular momentum mode was designed for OAM mode multiplexed amplification, demonstrating amplification of the third- and fourth-order OAM modes with ultra-low differential mode gain and average gain of >19 dB for four modes.
Article
Engineering, Electrical & Electronic
Xi Fang, Miaoxin Zhu, Zhufeng Suo, Yixin Fu, Ding Ding, Yingrong Chen, Qian Liao, Lei Zhang
Summary: This paper proposes a dual Volterra expansion based nonlinear equalization method for suppressing nonlinear interference in polarization division multiplexed optical OFDM/OQAM system. By using specially designed pilot sequences, the system robustness against nonlinear interference has been significantly improved.
OPTICAL FIBER TECHNOLOGY
(2022)
Article
Mathematics, Applied
Cuong M. Nguyen, Chee Pin Tan, Hieu Trinh
Summary: This paper investigates the simultaneous reconstruction of states and delays for nonlinear systems subject to input delays. The proposed method based on sliding mode observer effectively estimates state and identifies unknown delays without assumptions on differentiability of delays, and eliminates the need for the minimum phase condition required in traditional schemes. The effectiveness of the method is demonstrated through a numerical example.
APPLIED MATHEMATICS AND COMPUTATION
(2021)
Article
Mathematics
Teresa Faria
Summary: This paper provides sufficient conditions for the persistence and permanence of a family of nonautonomous systems of delay differential equations, including structured models from mathematical biology with nonmonotone nonlinear terms and either discrete or distributed delays. Applications to systems inspired by mathematical biology models are discussed.
Article
Optics
Alvaro Moscoso-Martir, Olaf Schulz, Arijit Misra, Florian Merget, Stephan Pachnicke, Jeremy Witzens
Summary: We introduce a concept and design of a 100 GHz PIC-based nonlinear frequency division multiplexed transmission system that stitches four b-modulated spectrally overlapping channels without frequency guard bands to obtain a continuous spectrum. To enhance performance, the receiver utilizes neural network-based equalizers. Simulation results demonstrate that this system effectively mitigates the nonlinear interaction issue between neighboring channels, which even a neural network equalizer alone would struggle to solve. The system achieves a transmission distance of 960 km with a raw data rate of 333 Gbps per polarization and a BER well below the SD-FEC limit for every subcarrier.
OPTICS COMMUNICATIONS
(2023)
Article
Mathematics, Interdisciplinary Applications
Wang Mei-Qi, Ma Wen-Li, Li Yuan, Chen En-Li, Liu Peng-Fei, Zhang Ming-Zhi
Summary: This paper analyzes a class of piecewise nonlinear systems with fractional differential delay feedback control. The average method is used to solve the nonlinear system and obtain the amplitude-frequency relationship. The correctness of the analytical solution is verified by numerical solution, and the effects of system parameters on the amplitude-frequency characteristics are analyzed. Finally, the dynamic analysis of the system is conducted, and periodic motion, period doubling motion, and chaos are observed with the change of perturbation parameters.
CHAOS SOLITONS & FRACTALS
(2022)
Article
Mathematics, Interdisciplinary Applications
Jose J. Oliveira
Summary: This paper provides sufficient conditions for the global asymptotic stability of a general n-dimensional nonautonomous and nonlinear differential equation with infinite delay. The main stability criterion depends on the delay size on the linear part and the dominance of linear terms over nonlinear terms. The obtained theoretical stability results are applied to answer open problems and generalize a bidirectional associative memory neural network model with delays. A numerical example is given to illustrate the novelty of the results.
CHAOS SOLITONS & FRACTALS
(2022)
Article
Engineering, Electrical & Electronic
Hui Li, Yonggui Kao, Yangquan Chen
Summary: This study investigates the stability of fractional-order nonlinear systems with state-dependent delays. The state-dependent delays, unlike usual time-dependent delays, make the delays relative to the states, resulting in uncertainty when historical state information is used. A lemma on Riemann-Liouville derivative is introduced to ensure the monotonicity of the considered function. Based on the Lyapunov method, several sufficient criteria are presented to guarantee the Mittag-Leffler stability of the discussed systems. Three examples, including practical applications in submarine positioning models, are provided to illustrate the correctness and applicability of the theoretical conclusions.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS
(2022)
Article
Engineering, Electrical & Electronic
Abhishek Mani Shukla, Sumanta Gupta
Summary: To exploit the advantages of multimode fiber (MMF)-based transmission, multichannel transmission with wavelength division multiplexing (WDM) is used to replace single-wavelength transmission of OAM modes. In an experimental study, the successful transmission of two OAM mode groups multiplexed signals jointly with three channels over a 1 km conventional MMF is demonstrated. The achieved bit error rate (BER) is found well below the required pre-FEC BER without using any MIMO-DSP.
IEEE PHOTONICS JOURNAL
(2023)
Article
Physics, Multidisciplinary
Wang Jian, Wu Chong-Qing
Summary: Mode-division multiplexing (MDM) technology based on few-mode fibers (FMFs) is a hot topic in optical fiber communication system. The complexity of the receiver can be reduced by using FMFs with low differential mode group delay (DMGD). The variational method is proposed and optimized to analyze FMFs with higher refractive index, and the effects of fiber manufacturing errors on DMGD are discussed.
ACTA PHYSICA SINICA
(2022)
Article
Engineering, Electrical & Electronic
Christos Simos, Iraklis Simos, George Georgiou
Summary: Non-linear gain compression is introduced into a delay differential equation model for passively mode-locked semiconductor lasers, showing the impacts on gain/absorption dynamics compared to the original model. A comparison between the enriched delay differential equation model applied on a ring cavity and a travelling wave model applied on an equivalent Fabry-Perot cavity is performed, demonstrating the limits of quantitative and qualitative agreement between the two approaches.
OPTICAL AND QUANTUM ELECTRONICS
(2021)
Article
Optics
Stanislav Derevyanko, Muyiwa Balogun, Ofer Aluf, Dmitry Shepelsky, Jaroslaw E. Prilepsky
Summary: This paper presents theoretical analysis of achievable information rates in transmission systems using the nonlinear Fourier transform (NFT) for nonlinearity mitigation, focusing on continuous b-modulated systems. Through adiabatic perturbation theory and asymptotic analysis using Riemann-Hilbert problem, a simple input-output relation for arbitrary b-modulated transmission is obtained. The spectral efficiency for various single polarization b-modulated systems is estimated based on this model, showing excellent agreement between theory and numerical results in the presence of inline amplifier noise as the dominant source of spectral distortion.
