Graphene-integrated hybridized metamaterials for wide-angle tunable THz absorbers

Metamaterial absorbers with excellent absorption properties and real-time tunability are desirable for practical applications. In this paper, we design and numerically investigate a polarization insensitive wide-angle metamaterial absorber with tunable absorption strength formed by finite-length symmetric metallic plates and graphene sheet. This structure achieves a near perfect absorption, and remains highly absorptive with wide incident-angle, higher than 80% at 60o for TE mode and around 90% at 70o for TM mode. Absorption strength can be varied between 97% and 52% by controlling the Fermi energy of graphene while the operating frequency remains relatively stable. Also without the presence of a ground plane as in other conventional absorbers, waves outside of the absorption band are allowed to travel through. The absorbing principle and absorption tunability mechanism are elucidated using effective medium analysis and finite integration simulations.