Accelerating the Full-wave Simulation of Pyramidal Absorbers Using the Structure Symmetries

The problem of plane wave diffraction from pyramidal absorbers is considered. In a previous study, we have developed a hybrid method based on the R-matrix Fourier modal method (RFMM) and the mode-matching (MM) of fields for an efficient and robust analysis of this class of absorbers. The proposed technique benefits from the intrinsic discrete spectrum of the periodic structure in transverse directions and consequently avoids spatial discretization along the periodicity axes, thereby simulating the device with minimal computation cost. Nonetheless, the method suffers from the requirement for solving a full system of linear equations, which leads to large computation costs when the performance of the absorbers at high-frequency bands is modeled. In this paper, we present the methodology for taking advantage of the structure symmetries and the consequent modes parity to drastically reduce the computation costs. The example of VHP pyramidal absorbers is outlined and convergence analysis is performed.