Polarization modulation by vanadium dioxide on metallic substrates

Abstract

Vanadium dioxide (VO 2 ) undergoing phase transition is known alters the polarization state of light in reflection owing to large changes in complex refractive indices. While this effect is promising for optical modulation applications, the usual VO 2 films on dielectric substrates tend to offer limited tunability for polarization modulation. In this paper, we show that metallic under-layers greatly enhance the performance by widening the spectral range and include visible wavelengths, by increasing the polarization modulation amplitude, and by widening the range of workable incidence angles. The imaginary part of the refractive index in the metallic layer is found to increase the relative phase shifts between s-and p-components of polarization as well as increasing the reflectance.

Controlling light polarization with VO2 films

“…Second, small reflection amplitudes tend to occur at high angles (for example near Brewster's angle for p-polarization), which lowers efficiency and limits available polarization states. We therefore looked at the possibility of attaining lower incidence angles by means of metallic substrates [4]. Figure 2 shows similar calculations as those of Figure 1 but with a gold underlayer.…”