Lifetest system for assessing reliability of high-power semiconductor laser diodes

High power semiconductor laser diodes are widely used for fiber laser pumping, solid-state laser pumping, materials processing, cosmetic treatment, laser display, solid-state lighting and military applications. Existing and emerging applications push the technology of high-power semiconductor laser diodes to even wider range of wavelengths, higher power and brightness, lower cost of manufacturing and the most importantly, the improvement of reliability. However, the reliability assessment of multiple high-power laser diodes has been difficult and costly due to the high current, high-density heat flux, high optical intensity and the possibility of contamination in a long-term lifetest. The lack of high-performance lifetest systems has hindered the progress of high power laser diodes. In this paper, we report the design and implementation of a high-performance system for reliability testing of high-power semiconductor laser diodes. This system is capable of simultaneously aging 80 single-emitter diodes each outputting 10-20W optical power with the in-situ optical power and optical wavelength monitoring. The handling capacities are as high as 2KW and 4KW, respectively for optical power and heat dissipation. Many features are implemented to ensure correct and safe use of the system. Various temperature sensors are embedded inside the system to monitor the temperatures of the cooling water, the temperature of the air and the temperatures of the heat sinks. Flow rate of the cooling water is monitored and controlled. As required for long term lifetest, the system provides a class-100 clean environment and a controlled temperature for laser diodes under test. The system is used in multi-cell acceleration aging of high-power, high-brightness 9xxnm semiconductor laser diodes manufactured by Shenzhen Raybow Opto Inc.