Near-Perfect THz Absorber with Wide Range Tunability

THz absorbers have wide applications ranging from sensors and monochromatic detectors for narrowband absorbers to shielding and energy harvesting for broadband absorbers. Designing a THz absorber with perfect absorption is a challenging topic. In this work, we present a broadband THz absorber with bandwidth ranging from 0.9 to 1.3 THz and a near-perfect absorption > 90 %. The absorptance frequency can be tuned using low voltage application (0.2 - 5 V), from 1.3 to 10 THz while maintaining high absorptivity. In comparison with other structures, this absorber is ultra-thin (20 nm - 160 nm) with a simple structure based on 2D materials (graphene, MoS2, phosphorene) without including Au or other precious materials. It is easy to fabricate, cost-effective, and voltage-tunable through nearly the whole THz region. Although the structure is a broadband absorber its fractional bandwidth ranges from 20-45% which can be enhanced to a narrowband absorber in future works.