The Lasing Characteristics of GaN-based Two-dimensional Photonic Crystal Surface Emitting Lasers

Abstract

GaN-based photonic crystal surface-emitting lasers(PCSELs) with AlN/GaN distributed Bragg reflectors were fabricated and analyzed. Different lasing characteristics of GaN-based PCSEL has been determeined and demonstrated by the PC lattice constants. The laser emission behavior covered the whole PC patterns of 50 mu m in diameter. Under the optical pumping at room temperature, the PCSEL with PC lattice constant of 230nm shows a threshold energy density of about 2.7 mJ/cm(2). Above the threshold, one dominated peak emits at 420.11 nm with a linewidth of 1.1 angstrom. The lasing wavelength emitted from PC lasers with different lattice constants occurs at the calculated band-edges provided by the PC patterns which further shows different polarization angles due to the light diffracted in specific directions, corresponding exactly to Gamma, K, and M directions in the K-space. The PCSEL also shows a characteristic temperature of 148K and a spontaneous emission coupling efficiency beta of about 5x10(-3). Besides, the coupled-wave model in the PC hexagonal-lattice is applied to distinguish the discrepancy in threshold power and the corresponding coupling coefficient. The results show the lasing actions within Gamma, K, and M modes have the substantial relation between the threshold energy density and the coupling coefficient.