Broadband polarization-insensitive terahertz absorber based on heavily doped silicon surface relief structures

Abstract

Design, simulation, and measurement of a broadband polarization-insensitive terahertz absorber are presented. The absorber utilizes subwavelength surface relief grating structures on a heavily phosphorous-doped silicon substrate surface. Experimental results indicate that the absorber achieved over 90% absorption in a broad frequency range from 3 to 5.1 THz due to destructive interference of waves. Simulation results indicate that the design can be extended to a wider absorption bandwidth by optimizing the grating parameters, doping types, and doping concentration. This broadband polarization-insensitive absorber has potential applications in anti-reflection coatings and imaging systems.