Defect modes created by an elliptic defect in two-dimensional triangular photonic crystals

This paper presents the polarization properties of defect modes created by an elliptic defect in a two-dimensional photonic crystal composed of circular cylinders with a triangular lattice. It has been observed that adjustment of the defects’ symmetry results in the splitting of the dipole mode degeneracy, as predicted by group theory, and the magnitude of the frequency splitting increases as the aspect ratio of the elliptic defect increases. We also study the orientation effect of the elliptic defect on the defect modes. The results show that the frequency of the defect modes is independent of the orientation of the defect rods and the field distribution rotates by the same angle as the defects.