Coherent two-dimensional lasing action in surface-emitting laser with triangular-lattice photonic crystal structure

Lasing action of a surface-emitting laser with a two-dimensional photonic crystal structure is investigated. The photonic crystal has a triangular-lattice structure composed of InP and air holes, which is integrated with an InGaAsP/InP multiple-quantum-well active layer by a wafer fusion technique. Uniform two-dimensional lasing oscillation based on the coupling of light propagating in six equivalent Gamma-X directions is successfully observed, where the wavelength of the active layer is designed to match the folded (second-order) Gamma point of the Gamma-X direction. The very narrow divergence angle of far field pattern and/or the lasing spectrum, which is considered to reflect the two-dimensional stop band, also indicate that the lasing oscillation occurs coherently. (C) 1999 American Institute of Physics. [S0003-6951(99)03529-9].