Controlling light polarization with VO2 films

Complex-valued refractive indices generally impart unequal optical phase shifts to s and p light polarization components. In a phase-change materials, such as vanadium dioxide (VO2), this effect can be exploited for optical modulation applications in thin films. Adding to this relative phase shift, VO2 exhibits large refractive index changes during the phase transition, which is useful to modulate polarization. In this paper, we review our recent progress on polarization modulation of visible and infrared light interacting with VO2 films. Aspects to be discussed include the best conditions for phase and amplitude modulation, and enhancement by metallic underlayers. Thermal hysteresis of the refractive index and its effect on polarization states during the phase transition will be also discussed.