THEORETICAL-STUDIES OF GAINP-ALGAINP STRAINED-QUANTUM-WELL LASERS INCLUDING SPIN-ORBIT SPLIT-OFF BAND EFFECT

We studied the GaM-AlGaInP strained quantum-well laser characteristics , taking into account the spin-orbit split-off bands, When the well wi dth is kept constant at 85 Angstrom, the threshold current of the unst rained quantum-well structure is most degraded by the effect of the sp in-orbit split-off subbands, due to the larger hole density of states near the band-edge. While the linear gain of the compressive-strained quantum well is slightly changed by the effect, it has the lowest thre shold current with the lower threshold gain, In the tensile-strained q uantum-well structure, the spin-orbit split-off bands improve the diff erential gain because they increase the density of states at the valen ce band-edge, When the lasing wavelength is fixed at 630 nm, the thres hold current of the compressive-strained quantum well is the lowest as well, The tensile-strained quantum well has lower threshold current t han the unstrained quantum well, and this phenomena is not observed in the analysis without the spin-orbit split-off bands, However, the red uction of threshold current of the tensile-strained quantum well is sm aller than that of compressive-strained quantum well, The tensile stra in is more preferable for high speed modulation because of its large d ifferential gain, due to the mixing between the light hole and the spi n-orbit split-off subbands.