Bi-Functional Meta-Surfaces for Ultra-Wideband Absorption and Broadband Polarization Conversion

We demonstrate the dynamically switching of the ultra-wideband absorption and the broadband polarization conversion through a bi-functional hybrid meta-surface design consisting of periodic stacked vanadium-dioxide (VO2) rings coated with graphene resonators. More specifically, such a hybrid graphene VO2 meta-surface is capable of trapping electromagnetic fields with more than 95% absorption rate from 1.43 to 8.96 THz when we impose 0 eV Fermi energy level over the graphene array with conducting-state VO2. On the other hand, highly efficient linear-to-circular polarization conversion with greater than 0.95 ellipticity can be achieved from 1.24 to 3.57 THz when the graphene Fermi energy level is set as 1 eV with insulating-state VO2. The design scheme using hybrid meta-surfaces with contemporary tunable materials to achieve ultra-wide band reconfigurable multi-functionalities, should pave the way for more advanced manipulations of electromagnetic fields.