Ultra-Compact Optical Switches Using Slow Light Bimodal Silicon Waveguides

Switches are essential components in several optical applications, in which reduced footprints are highly desirable for mass production of densely integrated circuits at low cost. However, most conventional solutions rely on making long switching structures, thus increasing the final device size. Here, we propose and experimentally demonstrate an ultra-compact 2x2 optical switch based on slow-light-enhanced bimodal interferometry in one-dimensional silicon photonic crystals. By properly designing the band structure, the device exhibits a large group index contrast between the fundamental even mode and a higher order odd mode for TE polarization. Thereby, highly dispersive and broadband bimodal regions for high-performance operation are engineered by exploiting the different symmetry of the modes. Two configurations are considered in the experiments to analyze the dimensions influence on the switching efficiency. As a result, a photonic switch based on a bimodal single-channel interferometer with a footprint of only 63 μm
²
, a power consumption of 19.5 mW and a crosstalk of 15 dB is demonstrated for thermo-optic tunability.