A bi-directional metamaterial perfect absorber based on gold grating and TiO2-InAs normal hexagonal pattern film

Abstract

We present and study a bidirectional metamaterial-perfect absorber based on TiO₂-InAs regular hexagonal pattern thin films and gold grating. We employ the finite difference time domain approach for simulation. Multi-narrowband perfect absorption and ultra-wideband perfect absorption can alternate as the light source's direction changes. Four narrow-band absorption peaks developed at 987 nm, 1188 nm, 1510 nm, and 2091 nm, respectively, when the incident light struck the bottom. The corresponding absorption efficiencies were 99.69 %, 99.41 %, 98.54 %, and 98.97 %. The broadband region displays the properties of perfect absorption when incident light strikes the top. It should be noted that it is not affected by the polarization or angle of the incidence. With an average absorption efficiency of 96.02 %, the structure attains over 90 % absorption in the 3023 nm range (424–3447 nm). Second, the weighted absorption efficiency of the full spectrum is as high as 96.84 %, and the AM 1.5 solar radiation spectrum and the solar absorption spectrum are strongly coincident. Furthermore, the computation results show that the thermal radiation efficiency is greater than 95 % between 300 K and 1500 K. The electric field distribution revealed that the Fabry-Perot cavity resonance within the film, the surface plasmon resonance (SPR) on the surface of the InAs and TiO₂ regular hexagonal pattern films, the interstitial mode excitation between the films, and the excitation cavity coupling between cells of each unit were primarily responsible for the perfect absorption of broadband. The high-order resonant coupling in the FP cavity and the strong coupling between the local surface plasmon resonance and the FP cavity resonance in the metal grating's slit are the primary causes of the narrow band's perfect absorption. The suggested bidirectional metamaterial perfect absorber has significant promise for use in the disciplines of sensing, solar energy absorption, photoelectric detection, and photothermal conversion, as evidenced by its superb absorption and thermal radiation characteristics.