Minimization of the linewidth enhancement factor in tensile-strained quantum-well lasers

Means of minimizing the linewidth enhancement factor in tensile-strained semiconductor lasers are theoretically investigated using a detailed microscopic model including many-body effects, strain, and valence subband mixing. The effects of well width and strain are analyzed and fundamental trends in the behavior of the linewidth enhancement factor are highlighted. Qualitatively different behavior of the linewidth enhancement factor is observed in tensile-strained devices, as compared to compressive and unstrained devices. In particular, the linewidth enhancement factor in highly tensile-strained devices displays reduced sensitivity to the device threshold gain. In contrast to unstrained and compressively strained structures, such devices offer improved performance at wider well widths.