Single‐layer narrow‐band beam splitter based on a transparent grating with high‐spectral contrast and high‐angle sensitivity

Abstract

A report on the polarisation beam splitter with high-angle-resolved tunability in the visible spectrum, which was achieved in a single layer of transparent thin film of indium-tin-oxide (ITO). One-dimensional grating structures were etched into an ITO layer with a designed depth using inductively coupled plasma, where the remaining ITO acts as a waveguide. Enhanced reflection of light was observed when the retro-diffraction was overlapped with the waveguide resonance mode. A beam splitting ratio of 1:1 was achieved at 532 nm at a specific incident angle. This is a stable and efficient beam splitter with high contrast and narrow-band response. It can also be applied as tunable narrow-band filters, angle sensors or optical switch.