Enabling broadband efficient beam splitting based on ultra-thin reflecting metasurfaces

Abstract

In this paper, we present a scheme for achieving broadband efficient beam splitting based on homogeneous ultra-thin metasurfaces, which is composed of an ultrathin dielectric spacer sandwiched between periodic arrays of identical rectangular metal resonators and an optically thick metal film. Based on this scheme, three beam splitters for incident wavelengths in the ultraviolet (UV), visible, and infrared (IR) are designed and investigated numerically. Although these beam splitters exhibit polarization-dependent optical responses, each one still has an operational band in which the conversion efficiency remains above 90 % for any polarization incidence. The operational band is respectively 250–299 nm, 478–574 nm, and 1411–1700 nm for these three metasurface-based beam splitters. Moreover, we propose a dual-band beam splitter and a four-channel beam splitter based on this metasurface with MIM configuration. The operational window of the dual-band beam splitter respectively locates in the visible and infrared regions.