Tunable ultra-narrowband terahertz perfect absorber by using metal-insulator-metal microstructures

Abstract

An ultra-narrowband terahertz (THz) perfect absorber with metal-insulator-metal (PA-MIM) microstructures is presented. MIM microstructures is composed of Al disk on SiO2/Al/Si substrate. This MIM configuration will induce dipole-image interaction and cause an electromagnetic confinement between MIM microstructures to eliminate the reflection. Therefore, the design of MIM can absorb most of THz wave to realize the THz PA. The absorption intensity of proposed device could be reached 99% with an ultra-high Q-factor of 143. By modifying the gap between top and bottom Al disks of MIM, the electromagnetic response can be tuned from single-band to dual-band resonance. These resonances can be actively controlled the corresponding absorption intensities to possess tunability in application of THz switch and THz variable optical attenuator (VOA). This tunable ultra-narrowband THz PA-MIM paves a way to be an important role in THz applications, such as sensors, detectors, solar cells, coherent thermal emitters and so on. Keywords: Metamaterial, THz filter, THz resonator, Ultra-narrowband