STRAIN DEPENDENCE OF THE LINEWIDTH ENHANCEMENT FACTOR IN LONG-WAVELENGTH TENSILE-STRAINED AND COMPRESSIVE-STRAINED QUANTUM-WELL LASERS

Values of the linewidth enhancement factor alpha in InGaAs/InGaAsP ten sile- and compressive-strained quantum-well (QW) Fabry-Perot lasers ar e measured and compared to calculated values. The strain dependence of the measured values agrees with that of the calculated values: Values of alpha are smaller for tensile-strained QW lasers than for compress ive-strained QW lasers, and alpha decreases with the increase of tensi le or compressive strain. According to the model used in the calculati on, short-wavelength-composition barriers reduce alpha in compressive- strained QW lasers, and alpha for such lasers is expected to be as low as that for the tensile-strained QW lasers.