Transverse magnetic defect modes in two-dimensional triangular-lattice photonic crystals - art. no. 056614

We present a numerical study of the localized transverse magnetic (TM) defe ct modes in a two-dimensional, triangular-lattice photonic crystal. The sam ple consists of an array of circular, air cylinders in a dielectric medium (GaAs). The defect modes were calculated by using a parallel version of the finite-difference time-domain method on the Yee mesh. To validate our comp utations the results for the transverse electric case were checked against experimental results and the numerical results using a different method. We study the spatial symmetry for TM modes, obtained by changing the dipole e xcitation frequency. Also, we vary the defect-cylinder radius to tune the r esonant frequency across the band gap. The TM mode is found to be highly lo calized at the defect in the photonic lattice.