Omnidirectional gap and defect mode of one-dimensional photonic crystals containing negative-index materials

The omnodirectional gap in a one-dimensional photonic crystal, which contained a negative-index material (NIM), was analyzed. The gap was found in photonic crystal because of zero averaged refractive index mechanism. The edge of zero-n̄ gap was independent of incidence angle and polarization. But, after the introduction of impurity, defect mode was obtained inside the zero-n̄ gap showing weak dependence on incident angle and invariance with scaling.