Toward non-metallic infrared metasurface filters with electrical and thermal controllability

A bicontrollable metasurface containing VO2, a non-linear optical polymer, and teflon was simulated to function as a bandpass filter in the infrared spectral regime. The metasurface is a singly periodic array of identical unit cells composed of parallel rectangular VO2 rods mounted on a silicon-dioxide substrate and covered with BAYI electro-optical polymer. The unit-cell dimensions are chosen such that the transmittance has a maximum in the 1418-to-l635-nm wavelength range, when the polymer face is normally illuminated by a plane wave with electric field parallel to the axis of the VO2 rods. When the crystallographic phase of VO2 is switched from monoclinc to tetragonal, the maximum transmittance redshifts from 1513 nm to 1656 nm, provided that no electrostatic field is present. However, when a dc potential of 50 V is applied across the polymer in the thickness direction, the minimum blueshifts from 1513 nm to 1418 nm at temperature T< 58°C temperature (VO2 is monoclinic), and from 1656 nm to 1513 nm at T> 72°C temperature (VO2 is tetragonal).