Low power coherent receiver for short-reach optical communication

Abstract

A low-power coherent receiver is enabled with enhanced performance for intra-datacenter reach optical interconnection applications using several techniques. The first is a coherent skew adjustment technique which enables lower-power baud-rate ADC sampling and baud-rate-spaced coherent equalization. The second is a real-valued or mixed-valued low-power coherent equalization technique, where a single-tap real-valued 4×4 MIMO equalizer plus four real-valued or two mixed-valued single-input single-out (SISO) equalizers are used for simultaneous polarization recovery, in-phase and quadrature (I/Q) phase error correction, and bandwidth equalization. The third is a power-efficient dual-DSP architecture to enhance coherent receiver performance, in which a complementary low-speed coherent DSP is introduced for optimal I/Q phase error correction and constellation decision parameters determination through more sophisticated algorithms that are too power hungry to be implemented in the primary high-speed DSP.