Gallium nitride ultra-wideband terahertz absorber based on periodic pyramidal array

Gallium nitride (GaN) has garnered significant attention due to its unique properties. Here, we present, for the first time, a polarization-independent ultra-wideband absorber in the terahertz band, consisting of a pyramidal GaN array and a GaN substrate. Numerical simulation results indicate that the designed absorber exhibits excellent absorption performance in the range of 0.39–1.98 THz, with a center frequency of 1.185 THz. The relative bandwidth ratio is 134.2%, and the absorption exceeds 90%. The equivalent circuit model further illustrates the ultra-wideband strong absorption characteristics of the proposed absorber. The simulated electromagnetic field distribution indicates that the perfect absorption of the designed absorber is attributed to the excitation of electromagnetic resonance. Additionally, due to the high structural symmetry, the absorber exhibits polarization-independent properties and maintains high absorption performance at large incidence angles. In the future, the proposed absorber will have a wide range of applications in optical applications, including detector devices, light detection equipment and solar energy collection systems.