Mode analysis of semiconductor lasers using lateral confinement by native-oxide layers

We have analyzed the lateral mode behavior of 980 nm InGaAs-AlGaAs lasers, where the waveguiding is carried out by oxidized AlAs layers beside a current aperture. The effective refractive-index step between the active and oxidized region has been calculated. We have found that the effective refractive-index step can be adjusted exactly by the thickness of the AlAs layer and its distance to the graded-index separate-confinement heterostructure region. We have compared this native-oxide-confined laser to a standard ridge-waveguide laser with respect to the lateral index step. Furthermore, we suggest a structure for a lateral separate confinement of carriers and optical waves. Experimental results are presented which are in good agreement with the numerical simulations.