Strained‐layer Ga0.7In0.3As‐AlGaAs‐GaAs graded‐index separate confinement heterostructure single quantum well lasers have been grown by molecular beam epitaxy with growth conditions selected to optimize the growth of each material. The lasers emit at a wavelength of 1.03 &mgr;m at 300 K. These lasers have threshold currents of 12 mA for 3 &mgr;m×400 &mgr;m devices and average threshold current densities of 174 A/cm2for 40 &mgr;m×800 &mgr;m devices. Studies of threshold current versus cavity length and width are compared with theoretical formulations. The threshold currents for lasers of various lengths and widths are significantly lower than those for previous strained‐layer lasers grown by molecular beam epitaxy and lower than those for strained‐layer lasers grown by organometallic vapor phase epitaxy.