Using a modified, O 2 -enhanced nonselective wet thermal oxidation process, deep-etched ridge waveguides in AlGaAs heterostructures containing λ = 808 nm InAlGaAs single quantum well or aluminum-free λ = 1.3 µm GaAsP/InGaAsN dilute nitride multi-quantum-well active regions have been directly oxidized to effectively provide simultaneous electrical isolation, interface state passivation, and sidewall roughness reduction. The resulting highindex-contrast (HIC) ridge waveguide (RWG) diode lasers show improved performance relative to conventional shallow-etched devices owing to both strong optical confinement and the complete elimination of current spreading, with 5 µm stripe width dilutenitride devices showing up to a 2.3 times threshold reduction and strong index guiding for kink-free operation. Oxidation of an AlGaAs graded-index separate confinement heterostructure is studied for varying O 2 concentrations, and the interface passivation effectiveness of the native oxide is studied through comparison with deposited SiO 2 and via a study of the stripe-width dependence of internal quantum efficiency and modal loss. The HIC RWG structure is shown to enable the operation of half-racetrack-ringresonator lasers with a bend radius as small as r = 6 µm.

InGaAs/GaAsSb type-II ‘W’ quantum wells (QWs) grown on InP substrates by metalorganic vapour phase epitaxy were investigated for potential emission wavelengths in the mid-infrared spectral region. Design studies using an 8-band k · p Hamiltonian model indicate that emission wavelengths near 3 µm should be achievable without strain relaxation. Improved electron confinement can be achieved by adding higher-energy band gap alloys such as AlAsSb or GaInP around the type-II ‘W’ active region. Comparisons of the simulations with experiment indicate that photoluminescence (PL) spectra are consistent with a type-II band alignment. 4-period type-II ‘W’ In0.8Ga0.2As (∼4.0 nm)/GaAs0.35Sb0.65 (∼1.5 nm) QWs separated by InP (5 nm) or AlAs0.767Sb0.233 (1.5 nm) barrier layers, demonstrate room-temperature PL emission at ∼2.1 µm

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Erratum: "Strain and relaxation effects in InAsP/InP multiple quantum well optical modulator devices grown by metal-organic vapor phase epitaxy" [J.Strain and relaxation effects in InAsP/InP multiple quantum well optical modulator devices grown by metalorganic vapor phase epitaxy