حسین شیرکانی

Nowadays, graphene is one of the most used materials in the manufacturing of optical instruments, such as sensors, photovoltaic 13 cells, and especially absorbers. The unrivaled ability of graphene in the formation of high-quality surface plasmons creates 14 extraordinary features for absorber devices. Here, by exploiting the nanoplasmonic structure consisting of one-dimensional 15 nanophotonic crystal made of graphene-silver half-ellipse grating next to the dielectric layer, the aim of this research is to achieve 16 broadband absorption and perfect absorber in addition to increasing single-layer and multi-layer graphene absorption by creating 17 surface plasmons and study the absorption spectrum in the near-infrared region. For this purpose, the studied nanostructure is 18 optimized under different incident angles, geometric parameters of the structure, and also the dielectric refractive index. The 19 proposed structure increases the absorption of graphene up to 85% along with wondrous absorption bandwidth over the entire 20 near-infrared region from 770 to 3000 nm. In addition to achieving broadband plasmonic perfect absorber, an ultra-broadband, 21 nearly perfect absorber, with the absorption of more than 80%in the whole near-infrared spectral zone has been introducedwhose 22 wide range of 1497 nm has an absorption above 90%. This range is far beyond the bandwidth of less than 1200 nm of 23 conventional absorbers. In addition to high strength and low angular sensitivity, this absorber has the wonderful ability to 24 effective absorb the solar radiation and can display abundant applications in solar cells, thermal emitters, and infrared detectors.