Topology Optimization of Dielectric Resonator in 3-D Waveguide Structure Considering Higher Mode Incidence

In this paper, topology optimization of dielectric material in a 3-D waveguide structure is presented. It is based on material sensitivity formulation in high-frequency domain. To obtain the dielectric distribution in a 3-D waveguide, the pseudo-source term is derived based on the differentiation of the objective function with respect to the electric field, and adjoint system is solved using the pseudo-source. In addition, a modified on/off method is used for complex 3-D model to improve the convergence of the solution. Issues that are encountered when implementing topology optimization with commercial EM software are explained, and their solutions are presented. Also, the duality of the E-field and H-field formulations of the material sensitivity is explored and summarized.