Fractionally-Spaced Equalizer Based on High-Order Statistics in Nonlinear Fiber Optics

Fiber non-linearity has become a major limiting factor to realize ultra-high- speed optical communications. We propose a fractionally-spaced equalizer which exploits a trained high-order statistics (mean, variance, skewness, etc.) to deal with data-pattern dependent nonlinear impairments in fiber- optic communications. The computer simulation reveals that the proposed 3-tap equalizer improves Q-factor by more than 2 dB for long-haul transmissions of 5,230km distance and 40 Gbps data rate. We also demonstrate that the joint use of a digital back propagation (DBP) and the proposed equalizer offers an additional 12 dB performance improvement due to the channel shortening gain. A performance in beyond 100 Gbps high-speed transmissions is evaluated as well.