Power-Efficient and Low-Loss Thermo-Optic Phase Shifter Enabled by Inverse Design

Photonic integrated chips offer great potential for applications in data centers, sensors, optical computing etc, due to large data transmission capacity, rapid transmission rate and CMOS compatibility. On-chip optical transmission mainly involves optical interference, and it puts certain requirements on the optical phase. Metal based thermo-optic phase shifters are often oversized and provide a slow response. In order to achieve tradeoff between energy consumption, optical loss, footprint and thermal crosstalk, we present an thermo-optic phase shifter based on a standard SOI platform by inverse design. The thermooptic phase shifter is engineered based on an N-doped heater. In the design process, enhanced particle swarm optimization algorithm is used to optimize the device performance. Simulation results show that the phase shifter exhibits a significant phase shift efficiency of 20.6 mW/π. In addition, a compact heater length of 72 μm and a low insertion loss of <0.0026 dB are achieved. With a favorable tradeoff of multiple performance metrics, the thermooptic phase shifter can be widely used in high-density photonic systems.