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

A bicontrollable metasurface containing VO
2
, 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 VO
2
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 VO
2
rods. When the crystallographic phase of VO
2
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 $T\lt 58^{\circ}\mathrm{C}$ temperature (VO
2
is monoclinic), and from 1656 nm to 1513 nm at $T\gt 72^{\circ}\mathrm{C}$ temperature (VO
2
is tetragonal).