Carrier-induced change in index, gain, and lifetime for (InAs)1/(GaAs)4 superlattice lasers

The carrier density dependence of gain, index, and carrier lifetime has been measured for (InAs)1/(GaAs)4 short-period superlattice lasers. The 500-μm-long lasers have a threshold current density of 200 A/cm2 and exhibit a small carrier-induced change in refractive index (Δn/ΔN∼2×10−22 cm3). The small Δn/ΔN also results in small linewidth enhancement factor (α∼1.1) of these lasers. The measured dependence of carrier lifetime on carrier density can be fitted to a bimolecular recombination model which suggests that radiative recombination is the dominant recombination mechanism in these structures.