Properties of two-dimensional double-layer photonic crystal with point defects

Abstract

This paper presents the properties of defect modes in two-dimensional double-layer photonic crystals with point defect in square and triangular lattices, considering the point defect is introduced by removing the cladding of the central rod. Using the plane-wave expansion method, it has been observed that the two-dimensional double-layer photonic crystals with point defect present defect modes within their bandgaps. Moreover, more than one defect modes have presence in triangular lattice structure, which almost have the same features as those of the traditional two-dimensional photonic crystal. Further evidence shows that the defect modes vary with the parameters of the defect, such as the radius, refractive index and orientation angle of the elliptical defect. The results show that the defect modes move to the low-frequency area with the increasing of the radius and refractive index of the defect. However, for elliptical defect, the frequency of the defect modes is independent of the orientation of the defect rod.