Design of tunable perfect absorber based on vanadium dioxide metasurface for sensing applications

A simple design of a two-dimensional periodic array of circular disc made of VO2 on a continuous silver film for sensing applications is presented. The spectral response of the proposed model is numerically investigated using Comsol multiphysics software based on finite element method. The results show that different spectral bands have absorptivity more than 90%. In addition, the proposed model exhibits a tunable behaviour of the absorption around the wavelength at 3.7μm which depends on the transition from metal to insulating phase of VO2. The physical origin of unit absorption at different resonant wavelengths have been investigated by considering the electromagnetic field distributions at the respective resonance wavelengths. Electromagnetic field profiles show that the enhanced absorption when VO2 film is in the metallic phase are primarily due to the localized and vertical cavity mode resonances, whereas in other case when VO2 is in the insulating phase, the unit absorption is due to the vertical cavity, the plasmonic and different order of the dielectric resonances. Further, the tunable nature of the absorbing properties of the proposed structure has been investigated by varying the geometrical parameters such as diameter and thickness of the circular disc. The effect of incident angle and lattice period on the absorption spectrum are also investigated. We strongly believe that these findings could have broad and significant impacts in photo-detectors, bolometers and sensor applications in midinfra-red wavelength band. © 2024 Elsevier GmbH