ANN assisted design of broadband near perfect metasurface absorbers exploiting InAs nanorods for visible light harvesting

This research focuses on the design of broadband, polarization-insensitive absorber layers based on all-dielectric metasurfaces for use across the entire visible light spectrum, i.e., 400-800 nm, for applications in solar cells and photovoltaic devices. The patterned metasurfaces utilize InAs nanorods with two different radii and heights, whose size diversity generates optical resonances at diverse wavelengths and increases the absorption bandwidth. The nanorods are based on a substrate of the same material, which is, in turn, backed by a SiO2 layer. Two absorbers are designed for different purposes, utilizing an accurate and efficient artificial neural network (ANN) model. The first absorber exhibits an extremely high average absorption of 99.5% under normal incidence. The second structure provides the highest angular stability by maintaining high absorption above 90% up to an angle of 70o for both transverse electric (TE) and transverse magnetic (TM) polarizations. Parametric analysis shows that the performance of the designed absorbers is robust to fabrication tolerances. The ANN-predicted results are verified by analytical approaches based on the electric polarizabilities of the nanorods. Compared to previous plasmonic and dielectric-based counterparts, the proposed absorbers exhibit superior performance.