A GaAs/AlAs coupled multilayer cavity structure was grown on a (001) GaAs substrate. The top cavity contains self-assembled InAs quantum dots (QDs) as optical gain materials for two-color emission of cavity-mode light. The bottom cavity layer was grown with lateral thickness variation in the wafer to investigate the effects of the thickness difference between the two cavity layers quantitatively. The frequency difference was minimum, and the intensity ratio of the two-color emission was unity when the optical thicknesses of the two cavity layers were the same. The emission intensity ratio was explained in terms of the electric fields at the top cavity region containing the QDs.
Double heterostructure wafers composed of p-InAs0.82P0.10Sb0.08/n-InAs0.94P0.04Sb0.02/n-InAs0.82P0.12Sb0.06 were grown on (001) oriented n-InAs substrates by liquid phase epitaxy. Stripe geometry lasers were fabricated from these wafers. The emission wavelength and the threshold current density of these lasers at 77 K were 3.0 µm and about 3 kA/cm2, respectively. Their threshold current density (Jth) was quite sensitive to the ambient temperature; the characteristic temperature T0, defined as T0=ΔT/Δ In Jth was 23 K in the temperature range between 77 K and 145 K.