Multiple-stripe and broad-area diode lasers operating at high power: aging and thermal degradation influences on performance

Abstract

This paper describes aging and thermal degradation influences on the performance of multiple-stripe and broad-area GaAlAs semiconductor diode lasers operating continuously at high power. Multiple-stripe and broad-area lasers emit large output powers (4 and 5 W) and large efficiencies (39 and 50%) at currents of 4 and 7.2 x <i>I_th</i>. At high currents of 4 x <i>I_th</i> multiple-stripe lasers emit beams containing multiple modes. These beams can have small consistent θ_pd divergences (13 deg) making it easy to couple into optical fibers for applications. Current increases in multiple-stripe lasers have little effect on their performance. Broad-area lasers can emit a single ν = 8 mode at currents up to 4.3 x <i>I_th</i> but have large divergences (60 deg) making it difficult to couple into optical fibers. During burn-in, aging lasers can emit erratic optical beams. After aging, the output power and efficiency of a multiple-stripe laser decrease (3 and 6%), while that of a modified multiple-stripe laser increase (3.5 and 5%). Thermoelectric cooling instead of heat-fin cooling increases the output power and efficiency of a multiple-stripe laser (7.4 and 6%), and longer shot intervals increases the output power (5.4%). Modified multiple-stripe and broad-area lasers emit similar broad beams centered on their optical axes, and the beams get broader as current increases.