Highly Efficient High-Brightness 970-nm Ridge Waveguide Lasers

In this letter we present new results on high power 970 nm ridge waveguide lasers based on an extreme double asymmetric epitaxial design. Due to an improved lateral-longitudinal design an M
²
-value below 1.1 and efficiency over 60% could be maintained at power levels slightly above 2 W. The lasers consist of a narrow mode-filter section at the back facet, a relatively broad section at the front facet for high power capability, and a tapered section in between with a very small taper-angle. We achieved the highest reported conversion efficiency for 1 W single lateral mode power to date of 67%, as well as the highest lateral (linear) brightness of 7.5 W/mm · mrad with 55% efficiency at 2.5 W. Results of first life time tests are presented which show the potential for commercial use.