Numerical Investigation on a Tunable Ultra‐Broadband GSST‐Based Perfect Metamaterial Absorber for Terahertz Applications

Abstract

An actively tunable novel ultra‐broadband terahertz metamaterial perfect absorber (MMPA) based on a phase‐change material (PCM) Ge 2 Sb 2 Se 1 Te 4 (GSST) is numerically investigated. The design comprises a multilayer structure consisting of four identical rectangular patches with two peanut‐shaped auxetic patterns of GSST as the resonator, a gold ground plane and a dielectric spacer of Li 2 GeO 3 (LGO). Simulation results exhibit a significant bandwidth of 8.64 THz spanning from 3.704 to 12.344 THz with a relative absorption bandwidth (RAB) of 107.68%, simultaneously maintaining absorption above 90% under normal incidence throughout the operating range. The absorption can be systematically tuned from 2% to 100% by varying the conductivity of GSST, substantiating various dynamic functionalities. Wave‐interference and impedance matching theories are analyzed to clarify the physical mechanism of the absorber. Systematic enhancement of the design and parameters are evaluated. Additionally, polarization sensitivity, incident angle effect in transverse electric (TE) and transverse magnetic (TM) modes and field distributions are investigated, which validate its stable operation for different polarization and incident angles. The ultra‐broadband absorption, tunable reconfigurable characteristics, and stable absorption up to a 45° of polarization angle make the proposed structure applicable to next generation devices such as sensors, optoelectronic switches, imaging, modulators, and cloaking.