Properties of one-dimensional ternary photonic crystals with negative-index

The bandgap properties and localized defect mode of one-dimensional ternary photonic crystals with negative-index materials are investigated by optical transfer matrix method. The results show that a new type of omnidirectional gaps is found. In contrast to the Bragg gaps, the properties (the central frequency and width of the gap) of such omnidirectional gaps are insensitive to the incident angles. When a defect layer is introduced, a defect mode appears inside the omnidirectional gap, and the spectral position of the defect mode is almost independent of incident angles and nearly invariant with the scaling.