Effect of carrier loss through waveguide layer recombination on the internal quantum efficiency in large-optical-cavity laser diodes

An analytical treatment for carrier distribution in optical confinement layers (OCLs) of semiconductor lasers with bimolecular recombination is developed. On the basis of this approach, the effect of OCL recombination on the internal quantum efficiency of a laser is evaluated. It is shown that this effect can lead to a rapid deterioration in efficiency with increased waveguide thickness at high enough currents, and also contributes to the efficiency decrease with current in a given structure. An asymmetric, narrow waveguide structure is shown to avoid this problem while still providing a good-quality beam.