Metasurfaces with thermal hysteresis

Abstract

As temperature cycles between 58 °C and 72 °C, VO2 undergoes a hysteretic transformation between the monoclinic phase and rutile phases, leading to a cyclical change in the complex refractive index that is indicative of semiconductor↔metal transitions. We simulated the visible/near-infrared spectra of the specular reflectance and transmittance of a metasurface incorporating a VO2 sheet and found that the extrema in both spectra blueshift from the cooling to the heating phases at a fixed temperature. This phenomenon is attractive for sensing temporal gradients of temperature.