The ever increasing demand for high-power, high-reliability operation of single emitters at 9xx nm wavelengths requires
the development of laser diodes with improved facet regions immune to both catastrophic and wear-out failure modes. In
our study, we have evaluated several laser facet definition technologies in application to 90 micron aperture single
emitters in asymmetric design (In)GaAs/AlGaAs based material emitting at 915, 925 and 980nm. A common epitaxy and
emitter design makes for a straightforward comparison of the facet technologies investigated.
Our study corroborates a clear trend of increasing difficulty in obtaining reliable laser operation from 980nm down to
915nm. At 980nm, one can employ dielectric facet passivation with a pre-clean cycle delivering a device lifetime in
excess of 3,000 hours at increasing current steps. At 925nm, quantum-well intermixing can be used to define non-absorbing
mirrors giving good device reliability, albeit with a large efficiency penalty. Vacuum cleaved emitters have
delivered excellent reliability at 915nm, and can be expected to perform just as well at 925 and 980nm. Epitaxial
regrowth of laser facets is under development and has yet to demonstrate an appreciable reliability improvement. Only a
weak correlation between start-of-life catastrophic optical mirror damage (COMD) levels and reliability was established.
The optimized facet design has delivered maximum powers in excess of 19 MW/sq.cm (rollover limited) and product-grade
980nm single emitters with a slope efficiency of >1 W/A and a peak efficiency of >60%. The devices have
accumulated over 1,500 hours of CW operation at 11W. A fiber-coupled device emits 10W ex-fiber with 47% efficiency.