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.