Umbrella-shaped graphene/Si for multi-band tunable terahertz absorber

We demonstrated a triple-band terahertz wave absorber, which consists of umbrella-shaped graphene metasurface array and a gold ground plane separated by a high-resistivity dielectric layer. Simulated results show that the proposed absorber has three distinctive absorption peaks at frequencies 0.506 THz, 1.638 THz, and 2.687 THz with the absorption rates of 0.998, 0.997, and 0.998, respectively. The terahertz absorber is valid to attain 0 degrees similar to 60 degrees range of incident angles for both transverse electric (TE) and transverse magnetic (TM) polarizations. For the graphene-based metasurface structures, the absorption curves can be tuned by controlling applied bias voltage. It is a promising candidate to design a high-performance absorber having the potential applications in bolometer, spectroscopic imaging, thermal detector, etc.