Surface-emitting tapered unstable resonator laser with integrated focusing grating coupler

We report on the fabrication and operation characteristics of a grating-based, surface-emitting, tapered unstable resonator laser with a trumpet shaped taper and a focusing outcoupler. The laser has a low threshold current density of 225 A/cm/sup 2/. It operates with a spatially coherent field and the near-field intensity indicates stable, filamentation free behavior up to at least 3/spl times/ the threshold current under continuous operation. At low drive currents the laser produces a nearly diffraction limited focused spot. With increasing current, the focused spot size increases and multiple side-lobes develop at high currents. We attribute this to a change in the phase of the emitted wavefront associated with thermal effects in the gain region.