Design and testing of a finite difference time domain system in cylindrical coordinates.

摘要

This thesis presents a Finite Difference Time Domain (FDTD) method in cylindrical coordinates for simulating structures with polar geometry and in particular a novel fibre structure. This method allows simulation of complex structures and a three dimensional representation not previously achievable.;The two dimensional FDTD method is derived and those characteristics of the method particular to cylindrical geometry are discussed. The mode resonances of metallic and dielectric waveguides simulated with the FDTD method agreed within 0.5% with the analytical solutions. The code was compared with commercially available FDTD code based on a rectangular approximation scheme, and proved to be far more accurate in simulating cylindrical structures. The modes of the novel fibre were simulated and found to be within 0.12% of those found using the Finite Element Method (FEM). The cylindrical scheme is shown to be useful for simulating three dimensional coupling situations not possible with the FEM system.