Defect in photonic crystal with negative index material

The transmission property of the photonic crystal containing negative index material is analyzed by means of transfer matrix method. It is demonstrated that a defect mode appears in the conventional Bragg gap and the defect mode is sensitive to the position of the defect cell. For the first time to our knowledge we introduce two defects into such a structure and discuss the dependence of the transmission on the interval of the two defect cells. It is found that a wide degenerate defect mode appears in the Bragg gap, and this degenerate defect mode splits into two different defect modes when the two defect cells become closer.