The stresses and photoelastic effects in stripe geometry GaAs-GaAlAs DH lasers with masked and selective thermal oxidation (MSTO) structure

We have analyzed the stress and photoelastic index distributions in GaAs-GaAlAs DH lasers with masked and selective thermal oxidation (MSTO) structure and have directly estimated the photoelastic index variation by a new method of Lloyd's mirror interference in a medium. We also studied their effects on the performances of this MSTO type of lasers and found its anomalous polarization characteristics, i.e., the output of the MSTO lasers consists of both TE and TM modes with nearly the same intensities which are out of phase. This phenomenon is explained qualitatively in view of the existence of the uniaxial stress component and antiwaveguide photoelastic index profile in the active region of the MSTO lasers.