A tunable broadband terahertz absorber based on graphene frequency selective surfaces

A broadband THz absorber is presented which is based on frequency selective surfaces (FSS). In order to make the design tunable, graphene is used in the patch layer. Random hill climbing algorithm has been applied to find the optimum design corresponding to the broadest bandwidth. A 84% fractional bandwidth at low terahertzs is obtained by the optimum design.