Aluminum Nitride Assisted Silicon Thermo-Optic Phase Shifter

Thermo-optic (TO) phase shifter serves as a fundamental component in large-scale integrated photonic chips, where its power consumption and response time significantly impact system performance. Various structures have been explored to enhance the performance of TO phase shifters, including spiral waveguide, suspended structures, and slow-light configurations. However, these structures often come with trade-offs in terms of footprint, robustness, bandwidth, or insertion loss. In this paper, we present a high-performance CMOS-compatible TO phase shifter that maintains a small footprint and minimal optical loss. Leveraging the high thermal conductivity of aluminum nitride (AlN), we achieve a π-phase shifting power of 14 mW for Mach–Zehnder interferometers (MZI) and 1.7 mW for ring resonators. The bandwidth of both MZI and ring resonator TO phase shifters reach 145 kHz. The proposed TO phase shifter demonstrates significant potential for large-scale integration into photonics chips, offering high power efficiency and broad bandwidth.