Ultra-Broadband Polarization- and Angle-Insensitive Perfect Meta-Absorber for Energy Harvesting and Thermal Infrared Detection

Broadband plasmonic metamaterial absorbers are highly sought after for their use in energy harvesting applications. Here, we theoretically demonstrate a nanophotonic perfect meta absorber comprised of a two-dimensional (2D) array of pyramidal multi-layered metal-dielectric (MD) structures. Each multi layered structure has 20 pairs of alternating MD layers comprising titanium nitride (TiN) and silicon dioxide (SiO2), with an optically thick TiN metal layer as back reflector. We theoretically show an exceptional average absorbance of 99.17% at normal incidence spanning ultra-broadband wavelength range of 0.3–5 μm, with peak absorbance of 99.99% at 1.28 μm wavelength. The proposed nanophotonic meta-absorber has an average absorbance of at least 94% for up to 60° of oblique incidence for random polarization. Thus, our proposed design is both angle-insensitive and polarization-independent. Our effective medium theory-based theoretical modeling comprehensively verifies the results obtained from full-wave simulations. Furthermore, the calculated figure-of merit for the proposed meta-absorber suggests that it can outperform some broadband absorbers recently reported in the literature. Thus, the suggested meta-absorber has potential applications in energy harvesting and thermal infrared detection.