Accelerated Degradation of High Power Diode Lasers Caused by External Optical Feedback Operation

We present results of investigations on high power broad area lasers in the spectral range between 780nm and 1060nm with different antireflection coatings on the outcoupling facet. Comparative life tests on high power semiconductor laser bars and single emitters with and without external optical feedback delivered significantly different results. Depending on the emission wavelength, we found different degradation rates and failure modes such as accelerated gradual degradation and catastrophic optical mirror damage caused by different energy reabsorption scenarios with respect to the energy gap of the substrate material.