ICI Mitigation for Dual-Carrier Superchannel Transmission Based on m-PSK and m-QAM Formats

We propose an intercarrier interference (ICI) mitigation scheme for dual-carrier superchannel transmission. Using the modified decision directed least mean square (DD-LMS) based multi-input multi-output (MIMO) processing, we can simultaneously realize both polarization division demultiplexing and ICI mitigation for PDM-m-PSK and PDM-m-QAM formats. Thanks to the innovative modification of frequency-shift operation, the MIMO equalization enables synchronous output of dual-carrier signals with robust performance against frequency offset, laser phase noise, as well as polarization mode dispersion (PMD). The experimental back-to-back transmission of PDM-16QAM signal has 8.3-dB OSNR improvement using the proposed MIMO processing. Three dual-carrier 160-Gb/s PDM-16QAM superchannels within 25-GHz grid are experimentally transmitted over 640-km standard single-mode fiber (SSMF), leading to net spectral efficiency of 5.7 b/s/Hz.