Low complexity and receiver IQ skew tolerant timing recovery and equalization scheme under baud-rate sampling short-reach coherent optical interconnection

Abstract

Coherent detection with high spectrum and oversampled digital signal processing (DSP) has been widely used in long-haul and metro optical communication, and power consumption is one of the most challenge for its application in energy-sensitive short reach optical connections, such as hyper-scale and ultra-capacity datacenter net works. With negligible chromatic dispersion (CD) and polarization mode dispersion (PMD) in short-reach interconnects, a low complexity and robust timing recovery and equalization scheme with baud-rate sampling is proposed and demonstrated experimentally, which aims to achieve a power efficient DSP. Instead of oversampled DSP with fully-connected butterfly equalization structure, baud-rate sampling DSP with one-tap connected butterfly structure must become the most power-efficient solution for short-reach optical interconnects, because spectrum aliasing and convolutional polarization mixing caused by CD and PMD can be ignored. Compared to conventional baud-rate and oversampled DSP scheme, the experimental results further confirm the advantage of the proposed scheme in BER performance and IQ skew tolerance. Additionally, the proposed scheme with baud-rate sampling and a simplified equalization structure can also save around 75% of power consumption with a negligible performance cost, compared to oversample DSP scheme.