Thin films of phase change materials for light control of metamaterials in the optical and infrared spectral domain

Nanophotonic component can be tuned by means of a thin phase change material (PCM) film put in its vicinity; PCM changes phases upon heat stimuli and thus provides a phase or amplitude optical contrast at the nanoscale. Vanadium dioxide (VO₂) is a promising material which undergoes semiconductor-to-metal phase transition at about 68 °C. In this work we combine its transition with a metamaterial made of golden nanodiscs, in the infrared spectral range. Metamaterial dimensions can be adjusted to provide the almost unitary absorption in the desired spectral range, which can be switched to zero absorption by changing the VO₂ phase. We further propose the optical switching of a large number of unitary cells by means of a near-infrared or visible laser. For given wavelength and power of the laser, we show how the spot-size can be adjusted to ensure that the whole VO₂ reaches the transition temperature. We further investigate the substrate influence. We believe that this approach can be generally used to design the metamaterial for a specific application, and find optimum experimental requirements for its switching.