LAUSR

Wide-angle polarization-insensitive triple-band perfect metamaterial absorbers (PMAs) based on single resonators are investigated. Generally speaking, the single resonator can only generate an absorption peak induced by the excitation of a fundamental resonance. Here, the designed absorbers with a single cave-ring resonator appear three perfect peaks for different polarization angles at 6.53 THz, 7.09 THz and 7.64 THz. For the case of the transverse electric (TE) mode, the resonant peaks are controlled by the angle of incidence. Compared with previous studies about angular stability, the absorptivity still exceeds 92% around 6.53THz even when the incident angle for the TE mode is up to 80°. For the case of the transverse magnetic (TM) mode, the absorptance at 7.64 THz is still greater than 92% even up to 70°. Simulated electric field (Ez) and magnetic field (/H/) distributions indicate that perfect absorption arises from the excitation of the multipolar response and surface plasmons. Besides, the complementary structure also displays three absorption peaks. We have demonstrated that simple ultrathin PMA has good absorption stability under an oblique incidence up to 70° at 2.62 THz, and that the resonance frequency at 2.62 THz is almost unchanged for the incident angle ranging from 0° to 70°. These proposed absorbers may be used in many applications, such as THz imaging, sensors, and detectors.