Coupled-Core Fiber Design For Enhancing Nonlinearity Tolerance

Publication Date: 4/8/2019

Event: SubOptic 2019

Reference: pp. 1-5, 2019

Authors: Fatih Yaman, NEC Laboratories America, Inc.; Shaoliang Zhang, NEC Laboratories America, Inc.; Takanori Inoue, NEC Corporation; Kohei Nakamura, NEC Corporation; Eduardo Mateo, NEC Laboratories America, Inc., NEC Corporation; Yoshihisa Inada, NEC Corporation

Abstract: Fiber nonlinearity is a major limitation on the achievable maximum capacity per fiber core. Digital signal processing (DSP) can be used directly to compensate nonlinear impairments, however with limited effectiveness. It is well known that fibers with higher chromatic dispersion (CD) reduce nonlinear impairments, and CD can be taken care of with DSP. Since, maximum CD is limited by material dispersion of the fiber we propose using strongly-coupled multi-core fibers with large group delay (GD) between the cores. Nonlinear mitigation is achieved through strong mode coupling, and group delay between the cores which suppresses four-wave mixing interaction by inducing large phase-mismatch, albeit stochastic in nature. Through simulations we determine the threshold GD required for noticeable nonlinearity suppression depends on the fiber CD. In particular, for dispersion-uncompensated links a large GD of the order of 1ns per 1000km is required to improve optimum Q by 1 dB. Furthermore, beyond this threshold, larger GD results in larger suppression without any signs of saturation.

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