Polarization-independent and non-omnidirectional defect modes of one-dimensional photonic crystals with negative-index materials

Polarization properties of defect modes of one-dimensional photonic crystals with negative-index materials are investigated by optical transfer matrix method. It is found that the defect modes in the zero-average-index gap have a strong dependence on the incident angles and polarization. Through tuning the optimized parameters of the defect layer, a series of polarization-independent and non-omnidirectional defect modes is obtained with the increase of incident angle, which is not available in conventional one-dimensional photonic crystals. Based on these defect modes, we have designed low-, high- and band pass spatial filters which have a polarization-independent feature comparing with spatial filters of conventional photonic crystals.