Chapter 4: Wave optics and FDTD simulations

This chapter focuses on time-domain electromagnetic simulation using the finite-difference time-domain (FDTD) method in OghmaNano. The pages in this section are built around practical, runnable examples showing how optical fields propagate, scatter, interfere, and evolve in structured photonic systems.

While the primary emphasis is on full-wave FDTD simulations, the chapter also connects to complementary tools such as transfer-matrix methods (TMM) for thin-film stacks and mode solvers for guided structures. These methods are used where appropriate, but the main focus here is on time-resolved field behaviour, including pulse propagation, diffraction, resonant energy build-up, and detector response. The material is organised as a sequence of tutorials progressing from basic wave propagation to more complex photonic structures such as waveguides, resonators, interference systems, and integrated optical devices. Each example is designed to be directly runnable, allowing the user to move from setup to quantitative analysis of transmission, reflection, confinement, and time-domain energy flow.