Finite-Difference Time-Domain Simulation of Wave Transmission Through Space-Time-Varying Media

A comprehensive study on the Finite Difference Time Domain (FDTD) numerical modelling of space- and time-varying media is presented. We investigate the dynamic behavior of oblique incidence of both TM and TE electromagnetic fields on space-timemodulated gratings. In their general form, these media have electrical permittivity, magnetic permeability, and electrical conductivity modulated across both space and time. We provide the FDTDschemes, the Courant-Friedrichs-Lewy (CFL) stability condition and equations for both TM and TE wave illuminations of space-time-varying slabs, along with the boundary conditions for the FDTD scheme. Furthermore, with engaging illustrative examples, we showcase the versatility and applications of space-time-varying media.