Theoretical studies of GaInP-AlGaInP strained quantum-well lasers including spin-orbit split-off band effect

We studied the GaInP-AlGaInP strained quantum-well laser characteristics, taking into account the spin-orbit split-off bands. When the well width is kept constant at 85 /spl Aring/, the threshold current of the unstrained quantum-well structure is most degraded by the effect of the spin 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 threshold current with the lower threshold gain. In the tensile-strained quantum-well structure, the spin-orbit split-off bands improve the differential gain because they increase the density of states at the valence band-edge. When the lasing wavelength is fixed at 630 nm, the threshold current of the compressive-strained quantum well is the lowest as well. The tensile-strained quantum well has lower threshold current than the unstrained quantum well, and this phenomena is not observed in the analysis without the spin-orbit split-off bands. However, the reduction of threshold current of the tensile-strained quantum well is smaller than that of compressive-strained quantum well, The tensile strain is more preferable for high speed modulation because of its large differential gain, due to the mixing between the light hole and the spin-orbit split-off subbands.<
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