Adjoint-Based Design of a Crossed-Ellipse Absent THz Filter

In this work, we propose a crossed-ellipse metal mesh THz filters on thick substrates. These filters exploit the trapped-mode excitation via inserting a smaller crossed ellipse centered with the outer absent one. An optimization approach to control the bandwidth of metal mesh THz filters is presented. Adjoint sensitivity analysis is utilized to provide the derivatives of the objective function for the optimizer. EM simulations are carried out to illustrate the efficiency of the technique in varying the filter’s bandwidth about a certain operating frequency of 300 GHz.