Ultrasmall broadband wavelength and polarization router based on hybrid waveguide of monolithic-LiNbO₃

The nanoscale wavelength and polarization router, which can simultaneously separate wavelength and polarization modes, is an essential component of on-chip nanophotonic devices. Here, an on-chip wavelength and polarization router is realized experimentally based on a three-layer hybrid waveguide of Au-SiO₂-LiNbO₃ etched with asymmetric nano-cavities. The central area size of the device is only 1.60×1.96  μm². A broad operation band covers from 500 nm to 1150 nm with low cross talk of under 10 dB. The monolithic-LiNbO₃is introduced for the first time, to the best of our knowledge, to on-chip multichannel wavelength and polarization routers. This work plays a key role for dense chip integration, visible light displays, and communications, and can inspire LiNbO₃-based nanophotonic devices.