Current-modulated optical properties of vanadium dioxide thin films in the phase transition region

Vanadium dioxide (VO₂) is a correlated electron material which undergoes an insulator-metal transition proximal to room temperature. The large change of optical properties across this phase transition is promising for tunable optical and optoelectronic devices especially at infrared frequencies. We demonstrate the ability to locally tune the optical properties on the micron scale through a simple design consisting of two electrodes patterned on a VO₂ thin film. By current injection between the electrodes, a localized conducting path (metallic phase) can be formed within the insulating background. The width of the conducting path can be controlled by varying the applied current. Fourier transform infrared imaging shows that this current-modulated reflectance changes significantly over a distance on the order of the wavelength in the mid-infrared spectral range.