Temperature Distribution and Facet Coating Degradation Analysis of 808 nm GaAs-Based High-Power Laser Diode Bars

The degradation mechanism of 808 nm GaAs-based high-power laser diode bars (LDBs) which has 47 single laser diodes is investigated using infrared thermography, focused ion beam, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy techniques. We obtained the temperature distribution of the output facet and the results indicate that emitter 24, which is located at the center of the bar chip, exhibits the highest facet temperature, that is, 37.87 degrees C and 42.08 degrees C at operating currents of 20 A and 25 A, respectively. Thus, we made a sample of emitter 24 that was then studied in detail. The facet coating of this sample changed and degraded visibly in both constituent and thickness, which eventually resulted in the catastrophic optical damage (COD) of its output facet. We deduce that we can improve the performance and reliability of LDBs through optimizing their facet coatings.