O-band 4×32 Gbit/s CWDM receiver on a silicon nitride photonic platform with micro-transfer printed InGaAs/InP photodiodes

We present an O-band four-channel coarse wavelength-division-multiplexed (CWDM) receiver implemented on a silicon nitride (SiN) photonic integrated circuit (PIC) platform, enabled by micro-transfer printing of InGaAs/InP photodiodes. The PIC incorporates a cascaded Mach–Zehnder interferometer (MZI) lattice filter demultiplexer and four high-speed photodiodes. The demultiplexer achieves low insertion loss (1.7–2.4 dB) and crosstalk below -14 dB across the 1270–1330 nm grid. The printed photodiodes exhibit responsivities of 0.54–0.72 A/W across the four channels and a 33 GHz 3-dB bandwidth at 1310 nm under a −2 V bias. High-speed back-to-back reception of 32 Gbit/s non-return-to-zero (NRZ) signals is demonstrated on all channels, yielding open eye diagrams and bit-error rates (BERs) below 10 −4 at demultiplexer-received optical powers above −11 dBm, obtained without a transimpedance amplifier. These results underscore the potential of micro-transfer printed InGaAs/InP photodiodes on SiN as a scalable solution for high-speed O-band receivers in short-reach interconnects and optical I/O.