Optical gain of interdiffused InGaAs-As and AlGaAs-GaAs quantumwells

摘要

We have analyzed theoretically the effects of interdiffusion onnthe gain, differential gain, linewidth enhancement factor, and theninjection current density of In0.2Ga0.8As-GaAs andnAl0.3Ga0.7As-GaAs quantum-well (QW) lasers. Wenhave calculated the electron and hole subband structures including theneffects of valence band mixing and strains. The optical gain is thenncalculated using the density matrix approach. Our results show that thengain spectrum can be blue-shifted without an enormous increase in theninjected current density. Imposing an upper limit (416nA·cm-2) on the injection current density for a typicalnlaser structure, we find that the InGaAs-GaAs and AlGaAs-GaAs QW lasersncan be blue-shifted by 24 and 54 mn, respectively. Our theoreticalnresults compare well with the tuning ranges of 53 and 66 meV found fornAlGaAs-GaAs QWs in some experiments. This indicates that theninterdiffusion technique is useful for the tuning of laser operationnwavelength for multiwavelength applications