Reconfigurable metasurface-based 1 × 2 waveguide switch

Abstract

Reconfigurable nanophotonic components are essential elements in realizing complex and highly integrated photonic circuits. Here we report a novel concept for devices with functionality to dynamically control guided light in the near-visible spectral range, which is illustrated by a reconfigurable and non-volatile ( 1 × 2 ) switch using an ultracompact active metasurface. The switch is made of two sets of nanorod arrays of TiO 2 and antimony trisulfide ( Sb 2 S 3 ), a low-loss phase-change material (PCM), patterned on a silicon nitride waveguide. The metasurface creates an effective multimode interferometer that forms an image of the input mode at the end of the stem waveguide and routes this image toward one of the output ports depending on the phase of PCM nanorods. Remarkably, our metasurface-based 1 × 2 switch enjoys an ultracompact coupling length of 5.5 μm and a record high bandwidth (22.6 THz) compared to other PCM-based switches. Furthermore, our device exhibits low losses in the near-visible region ( ∼ 1 dB ) and low cross talk ( − 11.24 dB ) over a wide bandwidth (22.6 THz). Our proposed device paves the way toward realizing compact and efficient waveguide routers and switches for applications in quantum computing, neuromorphic photonic networking, and biomedical sensing and optogenetics.