A FDTD method for calculating defect modes in a two-dimensional photonic crystal consisting of anisotropic cylinders

A finite differece in time domain (FDTD) method is employed to calculate defect modes in a two-dimensional photonic crystal consisting of anisotropic cylinders of tellurium. In order to obtain a defect mode inside the complete band gap, we adjust the radius R-d of the central defect and radius R-n of the neighboring defects. It is shown that the defect modes for the E-polarization are not sensitive to R-n, while the resonance frequency for H-polarization varies regularly as R-n changes. When the filling fraction f = 0.4 (R = 0.3568 a), R-d = 0.55 a and R-n = 0.26 a, the defect mode has the same resonance frequency omega(0) = 0.2466omega(e) (where omega(e) = 2pic/a, a, c being lattice constants) for both E-and H-polarization.