Numerical Design of a 1:3 Optical Power Splitter Based on a 2×3 RI-MMI Coupler Using Silicon Waveguides for C-Band

Optical power splitters are essential components for constructing more advanced and complex integrated circuits. Power splitters based on multimode interference (MMI) couplers using silicon-on-insulator waveguides are highly promising for high-density photonic integrated circuits. This paper presents an optimized design through 3D-BPM numerical simulations of a 1:3 ratio optical power splitter with two inputs, featuring high phase stability. This design is based on a restricted interference multimode interference (RI-MMI) coupler configuration to reduce circuit length, with precisely defined input and output positions. Numerical simulation results demonstrate that the coupler exhibits low excess loss and stable phase difference over a broad wavelength response covering the entire C-band. Additionally, the proposed splitter has a large height tolerance of up to $\pm 10 \mathrm{~nm}$. The entire circuit occupies a small footprint of $6 \mu \mathrm{~m} \times 54 \mu \mathrm{~m}$, indicating high potential for applications in constructing high-density on-chip integrated systems and networks.