Thermally and electrically tunable narrowband absorber in mid-infrared region

The mid-infrared spectral range is critical for bio-sensing and gas detection. Existing methods for designing wavelength-selective absorbers involve two-dimensional (2D) and three-dimensional (3D) nanofabrication, which is exceedingly expensive, rendering these methods impracticable. The application of a plane multilayer configuration using Fabry–Perot (FP) resonance can help overcome these drawbacks. This paper presents the numerical analysis of an innovative narrowband absorber with a VO₂-graphene-based Fabry–Perot (VGFP) multilayer structure using thermally and electrically tunable methods to regulate light absorption in the mid-infrared region. The maximum thermal modulation of spectral absorbance ranges from 0.068 to 0.999. The FP resonance is the primary cause of the strong light absorption and is explained in detail using the multiple reflection interference principle and the impedance transformation method. The absorption ratio of each layer was obtained from the analysis of its electric field and energy. The spectral selectivity of the absorber was varied by changing the dimensions of each layer of the absorber. Additionally, the effect of the incidence angle and gate voltage on the spectral absorbance of the multilayer structures was analyzed. Finally, the sensing performance of the VGFP multilayer structure was investigated. The findings of this study can be referred to for designing tunable high-performance optoelectronic devices in the future.