Efficiency degradation due to carrier build-up in the broadened waveguides of high-power laser diodes: analytical theory and numerical validation

An analytical theory is developed for the optical loss, output and external efficiency degradation due to the buildup of free carriers in the optical confinement layer of large-cavity laser diodes operated high above threshold. On the basis of this theory, it is shown that asymmetric, non-broadened waveguides can be a viable, and possibly superior, alternative to symmetric broadened ones in high power laser diodes from the optical losses, output efficiency, and internal quantum efficiency points of view. The foundations of the theory are validated by numerical simulations using the commercial package Las tip™.