Ordered and disordered photonic band gap materials

We discuss a formulation and computer implementation of a new method that c an be used to determine the electromagnetic properties of ordered and disor dered dielectric and metallic cylinders, using periodic boundary conditions in one direction. We show results which exhibit strong parallels with the behaviour of electrons in disordered semiconductors, but also illustrate so me characteristics which clearly differentiate between photonic and electro nic behaviour. Among these are strong polarisation sensitivity and erects d ue to metallic absorption.