Non-metallic and angular-insensitive metasurface transmissive long-pass filter in the visible and near-infrared regions

In this Letter, we report on a non-metallic and angular-insensitive transmissive optical long-pass filter in the visible and near-infrared regions, which uses two sets of dielectric nanopillars grown on S i O 2 substrate with M g F 2 on the top. Coupled Mie resonances are generated from the two sets of dielectric nanopillars with different sizes so that high reflection and absorption are realized to steeply cut off the transmission in shorter wavelengths and to ensure a high transmission in longer wavelengths. A polarization-independent and wide-angular-insensitive (up to 60°) cutoff effect is realized within a surface layer that is only 399 nm thick. Double-beam ultraviolet interference lithography and sputter coating depositions are designed to efficiently fabricate the proposed metasurface with a multi-set of sub-nanostructures. Experimental results demonstrate that high isolation with an extinction ratio > 16.53 d B (19.54 dB in simulation) and steep cutoff with a cutoff slope > 0.013 n m − 1 ( 0.022 n m − 1 in simulation) in transmission can be achieved. The demonstrated device suggests an efficient way of designing and fabricating angular-insensitive optical filters with metasurfaces, which is of importance in applications such as the liquid crystal display, optical communication, and sensors.