We report high-power single-spatial-mode type-Ⅰ GaSb-based tapered lasers fabricated on the InGaSb/AlGaAsSb material system.A straight ridge and three different tapered waveguide structures with varying flare angles are fabricated to optimize the output power and spatial-mode performance.The best devices exhibit single-spatialmode operation with room-temperature output power up to 350mW in continuous-wave mode at an emission wavelength around 2.0 μm with a very small far-field lateral divergence angle,which is beyond state of the art in terms of single-spatial-mode output power.