High-Efficiency Thermo-Optic Phase Shifter Based on Thin-Film Lithium Niobate Platform

Thermo-optic phase shifters are essential components for thin-film lithium niobate integrated photonic chips, providing a stable and compact alternative to electro-optic phase shifters for static electric fields or low-frequency applications. Conventional thermo-optic phase shifters based on a straight waveguide require substantial electrical power, which pose a challenge for applications that require low power consumption. Adopting air trenches and undercuts can improve modulation efficiency by preventing heat diffusion. However, poor heat dissipation reduces the phase modulation speed. This work presents high-efficiency thin-film lithium niobate thermo-optic phase shifters based on folded waveguides. Compared to conventional straight-waveguide thermo-optic phase shifters, the power consumption of the presented thermo-optic phase shifters is reduced by 45.4% due to the enhanced interaction between the waveguides and the thermal fields, while maintaining comparable response time. The proposed thermo-optic phase shifters feature reduced power consumption, facilitating the development of high-density, large-scale, and compact photonic integrated circuits.