Design and demonstration of a compact silicon photonic 3-dB power and quadrature phase splitter using 2×2 RI-MMI coupler
DOI:
https://doi.org/10.54939/1859-1043.j.mst.114.2026.88-96Keywords:
3-dB power and quadrature phase splitter; Restricted interference (RI); MMI coupler; Silicon-on-insulator; Silicon photonic fabrication; High- performance.Abstract
Multimode interference (MMI) waveguides are widely used in silicon photonics for their broadband operation and low loss. We present a compact and high-performance 2×2 restricted-interference MMI (RI-MMI) optical power splitter on a silicon-on-insulator platform. By optimizing input positions and interference length, the device footprint is reduced to 6 µm × 65 µm without compromising optical performance. Simulations via 3D-BPM and 3D-FDTD show low excess loss (< 4.3 dB), minimal phase difference (< 2%), coupling ratio variation (-0.09 to 0.05 dB), and excellent balance (< –17 dB) across 1500–1600 nm. Two designs (32.5 µm and 34 µm lengths) were fabricated using 193 nm DUV lithography. The 34 µm device exhibited < 5 dB insertion loss and < –23 dB reflection in the C-band. These results demonstrate the RI-MMI splitter's suitability for integration in advanced photonic circuits, including phasor signal generation, QPSK modulation, and OFDM processing.
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