Narrow Vertical Far-Field 975-nm Broad-Area DFB Lasers for Wide Temperature Range Operation

We report on 100-mum-wide 975-nm distributed-feedback lasers with a cavity length of 2 mm, which deliver 2.4 W within a 14deg vertical far-field angle (full-width at half-maximum) and 35% power conversion efficiency in combination with a spectral linewidth of 0.27 nm (95% power content). The epitaxial design is a compromise between a narrow vertical far-field and a good power conversion efficiency, as required for application as a pump source. Narrow linewidth operation is sustained to 100degC, enabled by use of a grating with a high coupling coefficient.