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

The explosive growth of data and data-centric computing places stringent demands on the bandwidth and energy efficiency of data center interconnects, spurring the development of several 400G Ethernet standards [1]. Silicon-photonics-based solutions are of particular interest for low cost 100+Gb/s/λ optical transceivers. Microring modulators (MRMs) can significantly scale the size and power of optical TX (OTX) compared to Mach-Zehnder modulators being used today [2]–[9]. However MRMs suffer from three significant drawbacks that have limited their use in 100+Gb/s optical transceivers: (a) tradeoff between bandwidth and phase efficiency inherent to these resonant modulators, (b) high process and temperature (P/T) sensitivity, and (c) non-linear electro-optic (E-to-O) characteristics. This paper presents a 3D-integrated 112Gb/s PAM-4 OTX with electronic nonlinear pre-distortion (NL-PD) and nonlinear FFE (NL-FFE) to compensate MRM nonlinearity and integrated thermal control (TC) to mitigate P/T sensitivity.