Theory of Gain, Modulation Response, and Spectral Linewidth in AlGaAs Quantum Well Lasers

We investigate theoretically a number of important issues rent have been considered before [ 151, [ 161, although the related to the performance of AlGaAs quantum well (QW) semicongain saturation effect was not explicitly treated, In Section ductor lasers. These include a basic derivation of the laser gain, the linewidth enhancement factor a, and the differential gain constant in I11 the fundamental properties of differential gain are dissingle and multiple QW structures. The results reveal the existence of cussed, and then the effects of QW structure parameter on gain saturation with current in structures with a small number of wells. the laser dynamics are investigated. In Section Iv, the They also point to a possible two-fold increase in modulation bandwidth linewidth enhancement factor cy and the spontaneous and a ten-fold decrease in the spectral laser linewidth in a thin QW emission factor are studied and the attainable reduction of laser compared to a conventional double heterostructure laser. the linewidth by the use of the optimum QW structures is considered. The results indicate that the modulation band