All-dielectric ultra-thin metasurface angular filter

An all-dielectric double-layer grid grating is proposed and demonstrated theoretically and experimentally to realize the angular filtering effect. The theoretical results show that the transmission of the double-layer grid grating drops sensitively, as the incident angle increases under TM incidence at the designed resonant wavelength. The transmission is almost 0 (i.e., the entire incident light is reflected) when the incident angle increases to over 12°, which exhibits excellent angular filtering behavior. Double-beam interference lithography and sputter coated depositions are utilized to fabricate the proposed angular filter. The experimental results show that the divergent angle of the transmitted beam through the angular filtering sample at the wavelength of 633 nm is 7.76°, and the transmission is as high as 0.936 at normal incidence. The ultra-thin all-dielectric angular filter is very easy to fabricate in a large area, which has important applications in directional lighting and image processing.