High Performance Mach–Zehnder-Based Silicon Optical Modulators

Silicon photonics is poised to revolutionize several data communication applications. The development of high performance optical modulators formed in silicon is essential for the technology to be viable. In this paper, we review our recent work on carrier-depletion silicon Mach-Zehnder-based optical modulators which have formed part of the work within the U.K. Silicon Photonics and HELIOS projects, as well as including some recent new data. A concept for the self-aligned formation of the p-n junction which is flexible in the capability to produce a number of device configurations is presented. This process is the key in having performance repeatability, a high production yield, and large extinction ratios. Experimental results from devices which are formed through such processes are presented with operation up to and beyond 40 Gbit/s. The potential for silicon photonics to fulfill longer haul applications is also explored in the analysis of the chirp produced from these devices and the ability to produce large extinction ratios at high speed. It is shown that the chirp produced with the modulator operated in dual drive configuration is negligible and that an 18-dB dynamic modulation depth is obtainable at a data rate of 10 Gbit/s.