SATURATION AND LOSSES IN AN OPTICAL SEMICONDUCTOR QUANTUM-WELL AMPLIFIER

The results obtained from luminescence measurements made on one-dimens ional optical amplifiers are reviewed. The investigated samples are Ga As/(Ga, Al)As waveguiding structures containing a multiple quantum wel l structure as active element. The experimental data are compared with the results of a numerical self-consistent model of the optical ampli fier. The observed spatial dependencies of carrier and luminous densit ies are found to agree in a semi-quantitative way with the theoretical predictions. Saturation of optical amplification is caused by carrier depopulation through stimulated recombination, and by the loss of lig ht caused by scattering at sample defects and/or imperfect waveguiding . It is argued that the discrepancies found on the high-energy side of the grain spectra are caused by reabsorption of amplified light at th e edges of the amplifier.