Molecular beam epitaxial (MBE) growth of InP/Ga0.47In0.53As/InP double heterostructures has resulted in pulsed room‐temperature lasing at 1.65 &mgr;m. Thresholds as low as 3.2 kA/cm2for a 0.6‐&mgr;m‐thick layer has been achieved. These results were achieved by ’’premixing’’ the Ga and In together in a common source oven and precisely monitoring the Ga/In flux ratio during the growth of the Ga0.47In0.53As layer. Cd diffusion from a vapor source allowed us topdope the top InP layer in the as‐grown MBE wafer.