Monolithic 4 × 112 Gb/s PAM4 Optical Receiver for Optical I/O

A monolithically integrated optical receiver comprising a four-channel microring-based WDM array, Ge-Si photodetectors (PDs) and a co-designed high-speed electronic front end is presented. The receiver achieves 112 Gb/s PAM-4 operation per channel with a power consumption of 0.71 pJ/bit and a bandwidth density of 437.5 Gb/s/mm². The four-channel wavelength division multiplexing (WDM) array supports an aggregate data throughput of 448 Gb/s. These results demonstrate good optical filtering and detector performance, offering a practical path toward dense, high-speed monolithic integration for optical interconnects.