Multimetal–VO2 Switchable Plasmonic Metasurface for High Contrast Optical Switching and Control at Short Wavelength Infrared Regime

Abstract

A switchable plasmonic metasurface is proposed for high contrast optical switching and control at short wavelength infrared regime. The metasurface is made of metal–VO₂–metal (MVM) multilayer layer pairs structured centrally with circular cylindrical ring aperture and investigated numerically using FDTD computations. Left circularly polarized (LCP) light excitation shows two resonant reflection dips at  ~ 2.5 µm and ~ 1 µm for semiconducting VO₂ and single resonant dip at ~ 1 µm for metallic VO₂. From the near-field analysis, we attribute the high wavelength reflection dip to the strong confinement of magnetic near-fields at the VO₂ regime and the lower wavelength reflection dip to the electric dipole resonance. The change in VO₂ phase from semiconducting to metallic or vice versa results in significant reflection switching (ΔR), > 60% for the higher wavelength (2.5 µm) reflection dip. The study also confirms the reflection switching to be polarization independent with large launch angle tolerance (> 10°). The design flexibility is further tested numerically by replacing various metal layers, central discs size, number of layer pairs and periods showing wide workable wavelengths ranging from 1.5 to 3 µm. Structuring the central discs system shows further modulation in the working wavelength and high wavelength reflection switching (ΔR) > 80% with large bandwidth > 500 nm (full width at half-maximum (FWHM)). The proposed metasurface is suitable for optoelectronic device integration for dynamic control and high contrast optical switching at the infrared regime.