Room-temperature emission is observed as long as 3.26 μm in optically pumped type-I quantum well lasers on relaxed epitaxial layers grown by molecular-beam epitaxy. A superlattice is used to filter dislocations in the metamorphic buffer to reduce Shockley–Read–Hall losses. The longest wavelength emission of 3.45 μm from these structures is observed at 170 K, and the brightest room-temperature laser emits 0.5 W/facet peak power at 2.81 μm. It has a low threshold power density of 169 W/cm2 and a differential quantum efficiency of 28%. The characteristic temperatures, T0 and T1, are 119 K and 171 K, respectively. Stimulated emission is observed in this sample at a maximum operating temperature of 370 K.