A broadband terahertz absorber using multi-layer stacked bars

TLDR

We present the simulation, implementation, and measurement of a broadband terahertz metamaterial absorber. The absorber is realized by stacking 12 metallic bars of varying lengths on three polyimide layers with equal spacing, merging successive resonance peaks to form a broadband absorption spectrum, and its mechanism is verified by a 9‑bar example. Measured absorption exceeds 95 % from 0.81 to 1.32 THz at normal incidence (FWHM 64 % from 0.76 to 1.48 THz), remains above 62 % up to 40° incidence, and the structure is robust against layer misalignment.

Abstract

We present the simulation, implementation, and measurement of a broadband terahertz (THz) metamaterial absorber. By stacking 12 metallic bars of varying lengths on three polyimide layers with equal spacing, a broadband absorption spectrum is formed through merging multiple successive resonance peaks. The measured total absorption exceeds 95% from 0.81 to 1.32 THz at the normal incidence and the full width at half maximum is 64% (from 0.76 to 1.48 THz). The absorption decreases with fluctuations as the incident angle increases but remains above 62% even at the incident angle of 40°. The physical explanation to the absorption mechanism is presented and verified by a 9-bar example, which exhibits narrower absorption bandwidth. It is also experimentally demonstrated that the proposed structure is robust against misalignment of each metallic layer.