Modeling of Finite Beams in Periodic FDTD Methods

This paper presents a finite-difference time-domain (FDTD) framework that accelerates the modeling of the interaction of infinite periodic structures with practical sources (such as Gaussian or Bessel beams) by exploiting periodic boundary conditions (PBCs). The technique involves the introduction of arbitrary beam-generating sources in periodic simulations via the array-scanning method (ASM). The proposed method is both efficient and practical, being naturally broadband and highly parallelizable. We present examples of Gaussian beams in free space and interacting with grating geometries, efficiently replicating the results of multi-period brute-force simulations.