Threshold gain and single-mode oscillation of two-dimensional photonic bandgap defect lasers

Defect laser behavior was simulated as a function of various parameters. When the crystal size was increased from 8/spl times/8 to 12/spl times/12 cylinders, the quality factor of the defect cavity increased from 6/spl times/10/sup 3/ to 5/spl times/10/sup 6/ while the threshold gain decreased by two orders of magnitude, It was predicted that a triangular-lattice photonic defect laser would be polarized in the /spl Gamma/-M direction. The defect laser studied usually showed multi-mode oscillation with a large defect radius, where the threshold gain was small. When the refractive indices of the cylinders and the defect, surrounded by air, were both 3.5, single-mode oscillation and a small threshold gain (4 cm/sup -1/) were, nevertheless, achieved at suitable device parameters that made the side-mode suppression ratio sufficiently large at 10/sup 3/. A single-mode oscillation and a small threshold gain (less than 20 cm(/sup -/1)) were also predicted over the entire defect radius range when the defect refractive index was decreased from 3.5 to 1.5.