Abstract

In this paper, we describe a novel update algorithm for the filter coefficients of the adaptive digital equalizer in coherent receivers, which is based on error signals evaluated in Stokes space and is insensitive to both phase-noise and frequency-offset. We also introduce an optimized decision rule in the Stokes space, which takes into account the exact statistics of noise and yields a performance improvement with respect to the minimum distance decision criterion. We compare the performance of the new algorithm to the standard constant-modulus algorithm (CMA) for polarization-multiplexed 16QAM modulation, achieving similar performance in the absence of phase noise, with comparable complexity. Differently from CMA, the proposed Stokes-space algorithm allows us to remove the phase offset between polarizations, thus enabling the use of a joint carrier-phase estimation algorithm on both polarizations, which in turns yields a nearly doubled phase noise tolerance.

© 2014 IEEE

Adaptive frequency-domain equalization in digital coherent optical receivers

Md. Saifuddin Faruk and Kazuro Kikuchi
Opt. Express 19(13) 12789-12798 (2011)

Time-domain digital pre-equalization for band-limited signals based on receiver-side adaptive equalizers

Junwen Zhang, Jianjun Yu, Nan Chi, and Hung-Chang Chien
Opt. Express 22(17) 20515-20529 (2014)

Stokes space modulation format classification based on non-iterative clustering algorithm for coherent optical receivers

Xiaofeng Mai, Jie Liu, Xiong Wu, Qun Zhang, Changjian Guo, Yanfu Yang, and Zhaohui Li
Opt. Express 25(3) 2038-2050 (2017)

All-Digital Timing Recovery and Adaptive Equalization for 112 Gbit∕s POLMUX-NRZ-DQPSK Optical Coherent Receivers

Xian Zhou, Xue Chen, Weiqing Zhou, Yangyang Fan, Hai Zhu, and Zhiyu Li
J. Opt. Commun. Netw. 2(11) 984-990 (2010)

Blind, fast and SOP independent polarization recovery for square dual polarization–MQAM formats and optical coherent receivers

Mathieu Chagnon, Mohamed Osman, Xian Xu, Qunbi Zhuge, and David V. Plant
Opt. Express 20(25) 27847-27865 (2012)