3D-BPM Simulation Design of A 2×2 Thermo-Optic Switch Using 2×2 RI-MMI Coupler on Silicon Waveguide

In order to build more sophisticated and intricate integrated circuits, optical switches are necessary parts. For high-density photonic integrated circuits, optical switches based on silicon-on-insulator waveguide multimode interference (MMI) couplers show great promise. This study uses 3D-BPM numerical simulations of a 2×2 optical switch to offer an optimal design. With carefully specified input and output locations, this design is based on a limited interference multimode interference (RI-MMI) coupler setup to shorten circuit length. The coupler's broad wavelength response, encompassing the full C-band, S-band, and L-band, is characterized by minimal insertion loss and crosstalk, according to numerical simulation findings. The proposed switch demonstrates symmetric behavior, achieving nearly identical performance for both input ports. It also shows strong robustness to fabrication and operational deviations, maintaining stable operation with a waveguide height tolerance of ±20 nm and a temperature variation of ±7 K. Across a wide bandwidth of 100 nm (1500–1600 nm), the design achieves low insertion loss (as low as -0.3 dB) and excellent crosstalk suppression (ranging from -18 dB to -53 dB), confirming its high optical performance through numerical simulations.