Mid-infrared angled-grating distributed feedback laser

We report near-diffraction-limited output from an angled-grating distribute d feedback type-II W laser emitting near 3.4 mu m. For pulsed optical pumpi ng of a 50-mu m-wide stripe at 78 K, the far-field beam divergence angle wa s only 1.4 degrees. The slope efficiency was 64% of that for a conventional Fabry-Perot laser on the same bar. However, the spectral linewidth decreas ed by only a factor of 2. The beam quality was substantially better than th at for the Fabry-Perot laser out to stripe widths of at least 800 mu m. (C) 2000 American Institute of Physics. [S0003-6951(00)00422-8].