SERPENTINE SUPERLATTICE NANOWIRE-ARRAY LASERS

We report characterization and modeling of serpentine superlattice nan owire-array lasers, These samples were grown by molecular beam epitaxy on (100) n(+)-GaAs vicinal substrates, In-plane ridge-waveguide laser s with ridge stripes either parallel or perpendicular to the nanowire arrays have been characterized at low temperatures, The measured net g ain spectra at 1.4 K showed strong optical gain anisotropy such that t he TM mode gain became greater than the TE mode gain when the optical cavity was placed along the nanowire direction. This provides strong e vidence that the lateral quantum confinement in the serpentine superla ttice is stronger than the vertical quantum confinement, Optical gain spectra in the serpentine superlattice are calculated with considerati on of coupling between wires and homogeneous line broadening, A good f it to the measured polarization-dependent gain spectra is achieved whe n the lateral Al segregation and the homogeneous line broadening are c hosen to be 8% and 7 meV, respectively, This small but finite Al segre gation in the serpentine superlattice provides lateral quantum confine ment for holes, which results in significant anisotropy in the relatio n between net gain and injection current density.