Coherent Detection Only by 2-D Photodetector Array: A Discreteness-Aware Phase Retrieval Approach

A simple and spatially-flexible coherent receiver without local lights, optical hybrids, or spatial de-multiplexers is experimentally demonstrated; 2×10-Gbaud SDM QPSK signals were detected only by 2-D arrayed photodetectors based on a novel phase-retrieving technique.