A Library of Ultra-Compact Multimode Interference Optical Couplers on SOI

Abstract
A library of compact multimode interference (MMI) couplers with MMI region widths ranging from 1.1 μm to 3.2 μm is presented for 220-nm silicon-on-insulator-based photonic circuits. By optimizing the MMI geometrical parameters and considering the Goos-Häanchen shift, insertion losses of lower than 0.1 dB with moderate experimental errors are achieved for 3-dB MMI power splitters at C band, with the power imbalance around 0.2 dB.