Software was developed for solving Maxwell’s equations using the finite-difference time-domain method, and was used to study 2D and 3D dielectric composites. The software was written from the ground up to be fast, extensible, and generalized for solving any finite difference problem. The code supports parallelization, allowing solutions to be obtained quickly using a beowulf cluster. An extension to the basic FDTD plane wave source was derived, allowing for the creation of angled, periodic, unidirectional plane waves on a square grid. 1D photonic crystal stacks were arranged in a square array and it was discovered that sizeable bandgaps for 2D and 3D geometries appear along the principle axes for different polarizations of the structure. Furthermore, bandgaps in different directions and polarizations could be made to overlap for reasonably large frequency ranges. The structure show promise for use as a low-threshold lasing and may be optimized to produce a complete photonic bandgap.