Comprehensive Investigation of Thermo-Optic Phase Shifters on a Multi-Layered SiN-on-SOI Platform

Thermo-optic phase-shifter is an important component widely used in various photonic applications such as optical neural network and LiDAR. Different methods have been proposed to improve the performance of the device. However, there is a lack of detailed quantitative comparison of such methods due to differences in fabrication platform and material properties. In this article, detailed investigation and comparison of 14 different thermal phase shifter designs on the same fabrication platform is provided. This includes the dimensions, material and heat dissipation approaches of the thermo-optic phase shifter. The comparison indicates that both suspended heater and doped silicon design could significantly improve thermo-optic phase modulation efficiency. On the choice of waveguide material, the electrical power consumption of SiN waveguide is about eight times higher than that of Si waveguide. Furthermore, the characterisation of thermal crosstalk and breakdown current of the thermo-optic phase shifters is also detailed. Such comprehensive investigation of thermo-optic phase shifters can serve as a useful design guideline for PIC designers.