Nonlinearity compensation and link margin analysis of 112-Gbps circular-polarization division multiplexed fiber optic communication system using a digital coherent receiver over 800-km SSMF link

Abstract

Nonlinear effects have been considered as the major limitations in coherent optical (CO) fiber transmission system. Digital signal processing (DSP)-based CO receiver with digital backpropagation (DBP) method has recently facilitated the compensation of fiber nonlinear impairments as well as compensating dispersion of optical fiber. In this paper, for the first time, a comprehensive design is presented for a newly introduced DSP-based CO receiver with the 8-quadrature amplitude modulation (8-QAM) circular-polarization division multiplexed (CPDM) fiber optic communication (FOC) system to investigate the impact of nonlinearities. We have examined the performance of nonlinearity compensating DSP-based CO receiver with DBP method and demonstrated that it can be effectively employed to mitigate the intrachannel nonlinearities in CPDM 8-QAM FOC system over 800-km SSMF link. Accordingly, by effectively compensating the fiber nonlinearities, we have analyzed the performance of bit error rate, optical signal-to-noise ratio (OSNR), optimum launch power, and investigate the link margin by evaluating OSNR margin for a specific launch power. Moreover, a CPDM technique helps as a very suitable means of maximizing the link capacity as well as enhancing the spectral efficiency of the FOC system.