A 3-D-Integrated Silicon Photonic Microring-Based 112-Gb/s PAM-4 Transmitter With Nonlinear Equalization and Thermal Control

Microring modulators (MRMs) with CMOS electronics enable compact low power transmitter solutions for 400G Ethernet and co-packaged optical transceivers. In this article, we present a 3-D-integrated 112-Gb/s pulse amplitude modulation (PAM)-4 optical transmitter (OTX) using silicon photonic MRM, on-chip laser, and co-packaged 28-nm CMOS driver. The 3-V-pp driver includes a lookup table (LUT)-based PAM-4 nonlinear equalizer to address static and dynamic MRM nonlinearities. An integrated thermal control method that is insensitive to input power fluctuations is proposed to compensate for the temperature sensitivity of MRMs. PAM-4 measurement results of our OTX at 112 Gb/s show that transmitter dispersion eye closure quaternary (TDECQ) <1.5 dB is achieved from 28 degrees C to 55 degrees C with 7.4-pJ/bit energy efficiency including on-chip laser.

Automated summary

This article presents a 3-D-integrated 112-Gb/s PAM-4 optical transmitter using microring modulators and CMOS electronics, achieving high energy efficiency and low power consumption. Nonlinear equalization and thermal control method are utilized to address static and dynamic nonlinearities of MRMs. The PAM-4 measurement results demonstrate excellent performance in compensating for temperature sensitivity and achieving efficient energy consumption.