INTERNAL 2ND-HARMONIC GENERATION IN CW ALGAAS SQW LASERS - THE FACET DEGRADATION MONITORING

The spectra of the second-harmonic (SH) radiation, generated in the se parate-confinement single quantum well (SQW) semiconductor AlGaAs/GaAs laser have been measured at various levels of the injection current. The observed correlation between laser and SH mode intensities is expl ained by taking into consideration the dispersion of the second-order nonlinear susceptibility of the GaAs active region. It is shown, that due to the high sensitivity of the SH signal to the semiconductor near -surface layer condition, the internal SH generation can be used for t he in situ diagnostics of the laser facet degradation processes.