Dielectric topological metasurfaces based in-plane control of light propagation by using valley degrees of freedom

Metasurface has garnered widespread attention due to its remarkable ability of precise light manipulation. The emergence of topological photonics has brought novel topological phenomena and holds the promise of introducing new optical functionalities to the metasurfaces. In this paper, by introducing valley degrees of freedom into metasurfaces, we design and numerically simulate topological-nanostructure-enabled on-chip chiral light propagation and multistage beam splitting, as well as holographic display by integrating a beam-splitting metasurface with valley photonic crystals (VPCs). Importantly, the proposed on-chip topological optical devices exhibit broadband response covering 1480–1660 nm and low transmission losses with the maximum efficiency reaching 82 %. Our work is expected to bring new optical functionalities to the metasurface based devices and can be widely applied in fields of optical fiber communications, on-chip optical transportation and smart wearable devices, which require high-efficiency, broadband and highly-integrated optoelectronic elements and devices.