29.3 A 40Gb/s PAM-4 transmitter based on a ring-resonator optical DAC in 45nm SOI CMOS

Silicon photonics is a rapidly maturing technology, promising to realize low-cost and energy-efficient optical links for rack-to-rack, within-rack datacenter applications, and supercomputer interconnects. Recently, the possibility of implementing ultra-power-efficient silicon photonic links using an unmodified state-of-the-art 45nm SOI CMOS process has been demonstrated [1]. This approach enabled the fabrication of millions of transistors and hundreds of photonic devices in the same chip to improve processor-memory link bandwidth, and opened a path to solving this traditional computation bottleneck.