Switchable reciprocal metasurfaces for infrared scene projection

Calibrating thermal detection systems for target recognition and accuracy can be challenging when live assets are not an option as a target. Infrared scene projection provides a cost effective and realistic alternative to assess missile capability. Infrared scene projection systems allow the generation of a thermally simulated scene for hardware-in-the-loop calibration of missile targeting. Previously, infrared scene projection technology has used resistor arrays, digital micromirror devices and laser diode arrays to name a few. Recent advancements in dynamic metamaterials provide a novel approach for the design of an infrared scene projection system. Reciprocal plasmonic metasurfaces are a metal-insulator-metal configuration of high aspect ratio dielectric pillars with sub-wavelength periodicity contained between a conductive top and bottom layer. Reciprocal plasmonic metasurfaces display an extreme sensitivity to ambient refractive index. This sensitivity in synergy with a conformal coating of a phase change material, such as vanadium dioxide, provide an excellent mechanism to implement a spatial light modulator as the scene generation component of an infrared scene projector. We report on the operating mechanism of the metasurface and characterize its sensitivity to changes in the ambient refractive index by applying a thin, conformal layer of aluminum oxide. We then expand on the experimental results by employing dielectric function data of optically characterized vanadium dioxide to inform calculations for predicting the effects of a thin conformal coating applied on the metasurface. Results indicate that pairing the sensitive metamaterial with the fast switching optical properties of vanadium dioxide provide a novel platform for infrared scene generation.