Vanadium dioxide thickness effects on tunable optical antennas

Vanadium Dioxide is an optically dense phase change material that has been applied to modulating the resonances of plasmonic structures resonant in the THz, infrared and optical ranges. It has been shown previously that fabrication of optical antennas on thin films of Vanadium Dioxide can result in a resonance shift of more than 10% across the phase change. This post-fabrication, dynamic tuning mechanism has the potential to significantly increase the possible applications of plasmonic devices. Here, we show that optical antenna arrays fabricated on differing thicknesses of Vanadium Dioxide supported by a silicon substrate show a dependence of their resonant wavelengths on this thickness. Along with the geometry of the antennas in the arrays this constitutes an additional degree of freedom in the design of the tuning range of these devices, offering further potential for optimisation of this mechanism. The potential extra blue-shift provided by optimising this thickness may be used, for example, in lieu of reducing antenna dimensions to avoid increasing antenna absorption and the additional plasmonic heating that can result.