Strained single quantum well InGaAs/AlGaAs graded‐index separate confinement heterostructure lasers have been grown by molecular beam epitaxy over nonplanar substrates. In addition to the low threshold currents providedinsituby lateral current blockingpnjunctions obtained by plane‐dependent doping of the amphoteric Si dopant, we observe variations in lasing wavelength, efficiency, and internal absorption as a function of the central (100) facet length. These variations are associated with increased indium composition in the strained quantum well which arises from incorporation of adatoms migrating from the low‐growth (311)Aside facets to the preferential growth (100) active area facets. Uncoated devices (750 &mgr;m×4 &mgr;m) have been found to have threshold currents as low as 6 mA (Jth=320 A/cm2) and exhibit single‐mode behavior to greater than 100 mW at a wavelength of ∼1.0 &mgr;m when reflectivity modified (90%/10%).