Extending omnidirectional reflection bands in one-dimensional photonic crystals

The presence of the Brewster point in one-dimensional photonic crystals restricts the possibility of achieving full omni-directional reflection at large incident wave vectors. We show that it is possible to achieve omnidirectional reflection in both rarefied and refracting incident media utilising periodic structures consisting of three or more distinct layers with differing refractive indices. In these ternary periodic structures the Brewster condition is not satisfied simultaneously at all interface and so strong reflection bands are achievable at any angle of incidence and polarisation state. Combining the ternary structure with layer chirping is necessary to open the full omnidirectional band.