Abstract
This study seeks to explain the effects of thermal runaway due to current competition between emitters in a laser diode bar using both experimental and simulation results. We have demonstrated a trend due to temperature and the evolution with aging using both experimental and simulation results. By-emitter degradation analysis was performed on two bars: 650 nm broad area laser bars and 980 nm tapered laser bars before and after aging. We observed that, a frown shaped temperature profile gave rise to a corresponding frown shaped profile, but the frown shaped power profile turned to a smile shaped profile with the evolution of time. The observed trend was confirmed using simulation results.
Highlights
Due to the increasing future needs for high-power semiconductor laser diodes i.e. in the generation of green electricity (Ertel et al, 2009), the research into their reliability and durability cannot be overemphasised
The trend shown in the experimental results were emulated using a multiple emitter scenario with 8 emitters for a calibrated 980 nm tapered laser bar
We have demonstrated a trend, which exist between a frown shaped temperature profile and the individual emitter power profile within a laser bar
Summary
Due to the increasing future needs for high-power semiconductor laser diodes i.e. in the generation of green electricity (Ertel et al, 2009), the research into their reliability and durability cannot be overemphasised. The pioneering of by-emitter measurements by Xia et al (2002), Tomm et al (2002) and Bull et al (2005), has helped in the understanding of the effect of temperature and other effects on laser diodes (packaging induce strain and defects). The effect of temperature (heating) is crucial because it enhances nonradioactive recombination, creating a feedback mechanism, which leads to the migration and condensation of point defects. This forms small dislocation loops, which lowers the quantum efficiency of devices. The progressive decrease in the optical output power along the device life is caused by recombination enhanced defect reactions (Kimerling, 1978; Jimenez, 2003) which is precipitated by heating
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