Graphene-Based Near-IR Plasmonic Wide-angle Broadband Perfect Absorber

Abstract

Nowadays, graphene is one of the most used materials in the manufacturing of optical instruments, such as sensors, photovoltaic cells, and especially absorbers. The unrivaled ability of graphene in the formation of high-quality surface plasmons creates extraordinary features for absorber devices. Here, by exploiting the nanoplasmonic structure consisting of one-dimensional nanophotonic crystal made of graphene-silver half-ellipse grating next to the dielectric layer, the aim of this research is to achieve broadband absorption and perfect absorber in addition to increasing single-layer and multi-layer graphene absorption by creating surface plasmons and study the absorption spectrum in the near-infrared region. For this purpose, the studied nanostructure is optimized under different incident angles, geometric parameters of the structure, and also the dielectric refractive index. The proposed structure increases the absorption of graphene up to 85% along with wondrous absorption bandwidth over the entire near-infrared region from 770 to 3000 nm. In addition to achieving broadband plasmonic perfect absorber, an ultra-broadband, nearly perfect absorber, with the absorption of more than 80% in the whole near-infrared spectral zone has been introduced whose wide range of 1497 nm has an absorption above 90%. This range is far beyond the bandwidth of less than 1200 nm of conventional absorbers. In addition to high strength and low angular sensitivity, this absorber has the wonderful ability to effective absorb the solar radiation and can display abundant applications in solar cells, thermal emitters, and infrared detectors.