Enhanced Optical Absorption and Thermal-Optic Effect of PtSe₂-on-Silicon Ultra-thin Micro-resonators

Integration of low-dimensional platinum diselenide (PtSe₂) with silicon photonics, leveraging its suitable band gap, inherent CMOS compatibility, and minimal lattice mismatch, presents a promising avenue for advancing mid-infrared (mid-IR) integrated optoelectronic devices. However, the study of PtSe₂-based heterogeneous silicon photonics is still in its nascent stage, particularly in the mid-IR spectral regime. Here, we demonstrate PtSe₂-on-silicon racetrack microring resonators (MRRs) incorporating a ten-layer PtSe₂ film. The MRRs, benefiting from a large evanescent field and significant intra-cavity energy density enhancement, exhibit notably increased light-PtSe₂ interaction. Our findings reveal enhanced absorption coefficients of 0.577 dB/μm and 0.462 dB/μm alongside a resonance shift rate of 0.24 nm/mW at 2200 nm wavelengths.