Power and speed analysis of miniaturized SOI y-branch Mach-Zehnder thermo-optic switches

We calculate the π-power and rise time for several 1×1 y-branch MZI SOI thermo-optic switches as a function of device size. These switches consist of waveguide core thickness ranging from 10 to 0.22 μm. Upon scaling the core thickness, the best power and speed performance occurs at 0.7 μm. Further miniaturization results in an increased power and reduced speed, mainly due to the mode expansion from the core into the cladding. We show that varying the MZI arm separation is an effective approach to improve the performance of miniaturized thermo-optic switches.