Properties of the defect modes in 1D lossy photonic crystals containing two types of negative-index-material defects

In this paper, the characteristic matrix method is employed to theoretically investigate the propagation of electromagnetic waves through one-dimensional defective lossy photonic crystals (PCs) composed of negative index materials (NIMs) and positive index materials (PIMs). We consider symmetric and asymmetric geometric structures with two different types of NIM defect layers at the center of the structure. The effects of the polarization and the angle of incidence on the defect modes in the transmission spectra of both structures are investigated. The results show that the number of the defect modes within the photonic band gap (PBG) depends on the type of the NIM defect layer and is independent of the geometrical structure. Moreover, it is shown that the defect mode frequency increases as the angle of incidence increases. This property is also independent of the geometry of the structure. The results can lead to designing new types of narrowband and multichannel transmission filters.