We report on the InAs/GaAs quantum dot (QD) lasers grown by gas-source molecular beam epitaxy. Ridge waveguide lasers were processed on the grown structure consisting of five-stacked InAs QD layers formed by InAs layers with slightly different thicknesses. Continuous-wave operation was achieved up to 80 degrees C and more than 50 mW optical power was collected from one facet at 20 degrees C. The characteristic temperature of the QD laser was measured as high as infinity in the temperature range of 80-185 K. In addition, the lasing lines covered the wavelength window as wide as 26 nm at 20 degrees C and 52 nm at 80K, respectively. By adjusting the cavity length, the lasing wavelength can be tuned in the range of 1.05-1.10 mu m. Both of the broad tuning wavelength and the wide lasing spectrum indicate that the QD lasers have very broad gain profile, which is highly desirable for making widely tunable lasers. (C) 2010 Elsevier B.V. All rights reserved.