The solid-source molecular-beam epitaxial growth of low-threshold GaAs-based GaInNAsSb lasers is discussed. A general narrowing of the growth window was observed with increasing wavelength, due to the increased nitrogen required (>= 1 %), and has historically made high-performance devices more difficult to achieve beyond similar to 1.35 mu m. The introduction of antimony and reduction in plasma-related damage from the rf nitrogen source dramatically improved material quality and widened the growth window. We validate these observations with 1.5 mu m edge-emitting ridge-waveguide lasers with cw threshold current densities as low as 440 A/cm(2), peak CW output powers of 431 mW, peak cw wallplug efficiencies > 16%, and pulsed output powers > 1 W. (c) 2005 American Vacuum Society.