AlGaAs ridge single-quantum-well graded-index separate confinement heterostructure (SQW GRIN-SCH) lasers with typical threshold currents of 9 mA and differential quantum efficiencies between 80% and 85% for 0-4mm-long cavities have been fabricated with molecular beam epitaxy. Continuous-wave light output increases linearly with the drive current up to approximately 15 times the threshold current. The lasers fail catastrophically at power levels between 65mW/facet and 85mW/facet, corresponding to power densities between 2-6 MW/cm2 and 3-4 MW/cm2. © 1986, The Institution of Electrical Engineers. All rights reserved.