22.9 A 1310nm 3D-integrated silicon photonics Mach-Zehnder-based transmitter with 275mW multistage CMOS driver achieving 6dB extinction ratio at 25Gb/s

Data centers and high-performance computing markets are growing at a fast pace, mandating power-efficient and cost-effective high-speed interconnects [1], tackling the large attenuation and crosstalk problems of metal interconnects and allowing higher miniaturization than hybrid photonics. The emerging silicon photonics technology lends itself to low cost short- and medium-reach optical communications. Externally modulated lasers allow transmitted optical signals with higher spectral purity than directly modulated lasers [2]. Discarding electro-absorption modulators (EAMs), which imply difficult hybrid integration of III-V materials on silicon, external modulation can be realized in silicon photonics by adopting Mach-Zehnder modulators (MZMs). A dual-drive push-pull configuration allows achieving optimal chirp performance [2], reducing dispersion in the fiber. Compared to ring resonator modulators, MZMs can operate over a much wider optical bandwidth without requiring device tuning. In particular, MZMs are almost insensitive to temperature variation and thus do not require power-hungry thermal controllers [3], which can significantly increase the overall power consumption of electro-optical transmitters.