Omnidirectional Gap and Defect Mode of One-dimensional Photonic Crystals with Negative-index Materials

Bandgap properties and the localized defect mode of one-dimensional photonic crystals with negative-index materials were investigated by optical transfer matrix method. A new type of omnidirectional gaps was found. In contrast to Bragg gaps, the properties (the central frequency and width of the gap) of such omnidirectional gaps are insensitive to the incident angles. The influence of incident angle changes and the thickness scaling on the spectral position of the defect mode when a defect layer was introduced were also discussed. These properties are of important significance in applications, such as omnidirectional or large incident angle filters in microwave technologies.