FDTD-Based Adjoint Sensitivity Analysis of High-Frequency Nonlinear Structures

A novel time-domain adjoint sensitivity analysis (ASA) approach is proposed. Our finite-difference time-domain (FDTD)-based approach accelerates wideband sensitivity calculations for high-frequency structures with nonlinear media. The introduced approach supports simulated problems with current sources or incident field excitation. Using only one extra system simulation, the sensitivities of a general objective function/response are estimated with respect to all the design parameters. The presented theory is based on first-order Maxwell’s equations rather than the second-order wave equation resulting in simple formulation and efficient memory storage. The accuracy and efficiency of the introduced algorithm are illustrated through a number of examples.