Mounting-induced strain threshold for the degradation of high-power AlGaAs laser bars

A new detailed approach has been developed, whereby the individual performances of the emitters comprising a laser bar are assessed separately as part of a larger coupled system. The results reveal the existence of a strain threshold, wherefore degradation of the emitter performances is only observed when the local packaging-induced strain is above a certain critical value. This degradation which occurs after aging, is manifested in an increase in the "apparent" threshold current and a decrease in the "apparent" slope efficiency of the individual emitters. This degradation is also revealed by the presence of facet defects as previously reported. These results suggest that measurement and control of packaging-induced strain will allow significant improvement in the degradation behavior of high-power AlGaAs laser bars.