Ultra-Broadband Terahertz Perfect Absorber based on Doped Silicon

The requirement for metamaterial perfect absorbers (MPA) based on doped semiconductors is steadily increasing due to the available matured fabrication and simulation technology. There is a particular interest in developing terahertz (THz) perfect absorbers using doped semiconductors for achieving characteristics such as polarization-independence, wide-angle, and broadband absorption. We report MPA based on patterned arrays of tapered micro-cylindrical structures of doped silicon to enable them with broadband, wide-angle, and polarization-independent response. In this work, we modeled the MPA structures using COMSOL Multiphysics to evaluate its electromagnetic wave response using the software's RF Module running in parallel on a Beowulf cluster. We evaluated the doped silicon MPA structures for its response in the frequency spectrum of 0.1 to 5.0 THz for transverse magnetic and transverse electric polarizations at the normal and oblique incidence up to 75 degrees. This proposed doped silicon MPA was found to support a perfect absorption for a wide frequency spectrum from 1.7 to 3.9 THz along with insensitivity towards polarization and incident angles up to 60 deg. The execution of MPA on simplified Beowulf cluster significantly reduced the simulations time by the orders of magnitude compared to the sequential simulations.