GaN photonic-crystal surface-emitting laser

Summary form only given. Recently, there has been growing interest in photonic-crystal surface-emitting lasers (PC-SELs) (1-4). The lasing principle exploited by the lasers is based on the band-edge effect in a two-dimensional (2D) PC, where the group velocity of light becomes zero and a 2D cavity mode is formed. The output power is coupled to the vertical direction by the PC itself, which gives rise to the surface-emitting function. PC-SELs have the following features: first, perfect, single longitudinal, and lateral mode oscillation can be achieved even when the lasing area becomes very large (for example, devices >300 mum in diameter) (1, 2, 4); and second, the polarization mode (2) and the beam pattern (4) can be controlled by appropriate design of the unit cell and/or lattice phase in the 2D PC. For example, unique beam patterns including doughnut shapes with radial or tangential polarizations have been successfully generated, which leads to a realization of super-high-resolution light sources that could be focused to a spot smaller than wavelengths (4, 5). Very recently, GaN PC-SELs have been realized in blue-violet wavelengths (6) by developing a unique method, named ldquoair-holes-retained over-growth (AROG)rdquo, in order to construct a 2D GaN/air photonic crystal structure. The device has successfully oscillated with a current injection at room temperature. In this presentation, the lasing principle, the device structures, a generation of unique beam patterns, and the very recent results on current-driven blue-violet GaN PC-SELs will be described.