A Low-Loss Crossing of Silicon Waveguides for Optical Switches on CMOS Platform

A novel waveguide crossing with low crosstalk and crossing loss was proposed and prototyped on the Si platform. The design consists a pair of tapered Si waveguides instead of a single waveguide at the crossing point, producing a mismatch of the mode fields between the input waveguide and crossing waveguide. The tapered Si waveguides with SiN
_x
outer cores demonstrate extremely low-loss waveguide crossing. An optical switch is prototyped by the crossing with a ring resonator, demonstrating a low-crossing loss and crosstalk, a high extinction ratio, and yet a small footprint.