High-efficiency anisotropic dual-band metasurface in the infrared region

The metasurface is a nanodevice capable of manipulating the phase, polarization, and amplitude of incident light, and it can be applied in many optical devices. However, there is always a problem with metasurface devices: the fixed operating wavelength. An anisotropic gradient metasurface composed of periodic arrangement of differently sized tellurium posts resting on the sapphire substrate is proposed. The metasurface can exhibit efficient beam deflection under x- and y-polarized incidences, but the operating wavebands are different for the two polarizations. When the x-polarized light is normally incident, the diffraction efficiency remains higher than 95% within the wavelength region from 7140 to 7260 nm. The diffraction efficiency remains higher than 95% within the wavelength region from 7840 to 7940 nm under the y-polarized incidence. Furthermore, the proposed metasurface can act as a polarizer in the +1 diffraction order direction within the wavelength region from 6460 to 6760 nm. We hope that the proposed metasurface can play an important role in future free-space optical devices. (C) 2019 Society of Photo-Optical Instrumentation Engineers (SPIE)