Graphene integrated rasorber at terahertz frequencies with functionalities of both absorption and transmission

Abstract

In this letter, a novel kind of graphene integrated dual-polarization rasorber is proposed in the terahertz regime. This two-dimensional rasorber is cascaded a top lossy layer, a middle dielectric spacer and a lossless layer at the bottom. Ultra-wideband impedance matching with functionalities of both absorption and transmission is achieved from 1.34 to 3.13 THz. The broadband absorptive characteristic which mainly originates from strong electric field confinement is produced by integrating graphene flakes into cross-frame resonators. On the other hand, the transmission band with low insertion loss is obtained using a complementary square ring resonator (CSRR). The proposed rasorber exhibits a good absorption performance from 1.27 to 2.43 THz and a low insertion loss at 2.8 THz. Oblique incidence stability and tunable absorption by varying chemical potential of graphene are also proved. The rasorber has further advantages of avoiding 3-D hollow lattices/air spacer and welding multiple lumped resistors, thereby greatly improving the planar integration of the structure in photovoltaic devices.