Integrated PAM-4 WDM Receiver by InGaAsP-Based Membrane PDs and SiN Demultiplexer on Si

We report a wavelength-division-multiplexing receiver based on heterogeneous integration of InP-based membrane photodetectors and a SiN arrayed-waveguide-grating demultiplexer on Si, which successfully receives eight-wavelength 56-Gbit/s 4-level pulse-amplitude-modulation signals with bit-error rates of less than 3.8 × 10
^-3
.