Low-crosstalk waveguide crossing based on 1×1 MMI structure of silicon-wire waveguide

Waveguide crossing based on a tilted multimode-interference (MMI) structure in high-index-contrast silicon wire is reported. For low crosstalk and low loss, crossing angle of MMIs is optimized. The measured crosstalk with the optimal crossing angle of 110° is -44 dB at wavelength of 1550 nm. This corresponds to improvement by more than 14 dB from previously reported crosstalk with 90°-crossings of MMIs.