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

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 similar to 2.5 mu m and similar to 1 mu m for semiconducting VO2 and single resonant dip at similar to 1 mu m 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 (Delta R), >60% for the higher wavelength (2.5 mu m) reflection dip. The study also confirms the reflection switching to be polarization independent with large launch angle tolerance (> 10 degrees). 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 mu m. Structuring the central discs system shows further modulation in the working wavelength and high wavelength reflection switching (Delta R) >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.