Threshold gain and gain-enhancement due to distributed-feedback in two-dimensional photonic-crystal lasers

The threshold gain (g(th)) of a two-dimensional (2D) photonic crystal distributed-feedback (DFB) laser composed of 8x8 dielectric cylinders was one order of magnitude smaller than that of an 8-pair 1D DFB laser with the identical refractive indexes. In the 2D finite-width photonic crystal laser, g(th) using the 1st photonic band was smaller than that using the higher photonic band, contrary to the expectation from the flatness of the photonic band structures. This unexpected g(th) is probably due to the longer optical path caused by the reflection at the side boundary. Moreover, g(th) using the 1st photonic band was the smallest in the Gamma -X direction of the square-lattice photonic crystal. The gain-enhancement using the 1st-3rd photonic bands were 10-30 in the 2D photonic crystal and that using the 3rd band was the largest. The gain-enhancement using the 1st photonic band of the 2D photonic crystal consisting of dielectric cylinders was larger than that of air cylinders. (C) 2001 American Institute of Physics.