A 112 Gb/s PAM4 Silicon Photonics Transmitter With Microring Modulator and CMOS Driver

Microring modulators (MRMs) with CMOS electronics enable compact low power transmitter solutions for 400G Ethernet and future on-package optical transceivers. In this paper, we present a 112 Gb/s PAM4 transmitter using silicon photonic MRM, on-chip laser and co-packaged 28 nm CMOS driver. We describe the impact of static and dynamic MRM nonlinearity on PAM4 signaling and present a dual path nonlinear pre-distortion technique to compensate both effects. PAM4 measurement results of our transmitter at 112 Gb/s show that TDECQ <0.7 dB is achieved from 30 degrees C to 60 degrees C while dissipating 6 pJ/bit. We also present link level measurements at 112 Gb/s PAM4 obtained by coupling this transmitter with our previously published CMOS TIA-based receiver, to demonstrate the feasibility of low cost optical transceivers through CMOS integration of optical interface circuits.