Mode Reflectivity and Waveguide Properties of Double-Heterostructure Injection Lasers

Abstract

It is shown that the mirror reflectivity for tightly confined planar waveguide modes becomes a function of both the waveguide and mode parameters. This dependence of the mirror reflectivity plays the dominant role in the selection of the oscillating transverse modes and explains why room‐temperature cs‐type double‐heterostructure lasers tend to lase in higher‐order TE modes. Experimental investigations show that the waveguide and mode parameters are qualitatively consistent with a dielectric step waveguide which is mainly perturbed by small gradients of the optical dielectric constant arising from impurity segregation.