The properties of (AIGa)0.5 In0.5P, strained GaxIn1-xP/(AIGa)0.5In0.5P heterostructures, and single quantum well (QW) laser diodes with Al0.5In0.5P cladding layers, prepared by low pressure organometallic vapor phase epitaxy, are described. The influence of biaxial strain upon the relative positions of the valence band edges are examined by analyzing the polarized spontaneous emission. Laser diodes with wavelength 620 < λ < 690 nm are also fabricated, using active regions of biaxially strained GaInP or AIGaInP. At longer wavelengths, threshold current densities under 200 A/cm2and efficiencies greater than 80% result from a biaxially-compressed GaInP QW active region. Short wavelength AIGaInP laser performance is hindered by the poor electron confinement afforded by AIGaInP heterostructures. Despite the electron leakage problem, good 630-nm band performance, and extension into the 620-nm band, is achieved with strained, single QW active regions. © 1994 IEEE