Properties of impurity band in one-dimensional photonic crystal coupled-resonator containing defect layers with negative refractive index

The transmission through one-dimensional photonic crystal coupled-resonator containing defect layers with negative refractive index is studied by using transfer matrix method. It is found that when the refractive index of defects is changed, the coupling effect between the defect modes is varied, which results in the change of the impurity band. Some sharp transmission peaks and a wide pass band appear at the same time in the for bidden band when the refractive index of defects is appopriate. So the structure can be used as both a multiple channel narrow-band filter and a wide-band filter at the same time.