Silicon Photonic Microring-Based 4 × 112 Gb/s WDM Transmitter With Photocurrent-Based Thermal Control in 28-nm CMOS
J. Sharma, Zhe Xuan, Hao Li, Taehwan Kim, Ranjeet Kumar, Meer Sakib, Chun-Ming Hsu, Chaoxuan Ma, Haisheng Rong, Ganesh Balamurugan, James Jaussi
Abstract
This work presents a hybrid-integrated 4- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> micro-ring modulator-based wavelength-division multiplexed (WDM) optical transmitter (OTX) in the O-band, suitable for co-packaged optics. It supports up to 112 Gb/s per wavelength using high-bandwidth micro-ring modulators (MRMs) together with nonlinear equalization in the driver electronics. A thermal control scheme using MRM photocurrent to sense process and temperature variations is implemented, enabling <0.05 dB TDECQ penalty over 10 °C. This compact photocurrent-based control method significantly reduces the hardware and packaging overhead required for ring-based WDM transceivers. Measurements from a 4- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> OTX with 28-nm CMOS electronic IC (EIC) and custom silicon photonic IC (PIC) show the OTX supports 112 Gb/s with <0.7 dB TDECQ across all four channels while dissipating 5.8 pJ/bit in the electronics.