Efficient thermo-optic phase shifters for photonic integrated circuits based on 500-nm-thick silicon on insulator

Integrated-optical thermo-optic phase shifters (TOPSes) are indispensable components for active light control in photonic integrated circuits (PICs). While mature on standard 220-nm silicon-on-insulator (SOI) platforms, new TOPS designs are required for emerging nonstandard SOI substrates, particularly those with 500 nm silicon and 1 μm buried oxide (BOX) layers, which are appropriate for III-V/silicon hybrid lasers. This paper presents what we believe to be a novel TOPS design specifically engineered for these substrates. Our design incorporates a rib waveguide with a deliberately tailored finite slab width, strategically mitigating the increased power consumption associated with these material specifications. This rib waveguide also ensures seamless, lossless integration with standard single-mode rib waveguides. Through systematic design, fabrication, and characterization, our TOPS achieved an average π phase shift power of 55.9 mW and a rapid response time of 7.09 μs. Comparative analysis against reference TOPSes revealed a remarkable 30% reduction in power consumption and ∼42% reduced thermal crosstalk. These superior performance metrics establish our TOPS as a vital building block for advanced silicon PICs on these crucial nonstandard SOI platforms.