THEORETICAL-ANALYSIS OF GAIN SATURATION COEFFICIENTS IN INP-BASED STRAINED-LAYER QUANTUM-WELL LASERS

The gain saturation coefficients of tensile-strained, lattice-matched, and compressive-strained InGaAs/InGaAsP quantum-well lasers (QWLs) ar e calculated from intrasubband relaxation times. The intrasubband rela xation times are in turn obtained within the random-phase approximatio n including carrier-carrier and carrier-polar-optical phonon interacti ons at room temperature. The effects of strain on the band structures are included by taking into account the strain-dependent coupling amon g heavy-hole, light-hole, and spin-orbit split-off subbands on the bas is of the multiband effective-mass theory. It is demonstrated that the gain saturation coefficient in tensile-strained QWLs is less sensitiv e to the amount of strain than in compressive-strained QWLs where it m arkedly increases with strain.