We report a high performance operation of quantum cascade lasers based on Single Phonon-Continuum depopulation (SPC) structures. The lasers exhibit low CW threshold current densities and high characteristic temperatures in the wide wavelength range between 4.5 and 10.8 μm. An 8.2 μm laser, despite a bare ridge structure which is extremely simple configuration without any intentional thermal dissipation equipments and any HR coatings, demonstrates the high device performance: a low threshold current density of 1.66 kA/cm2 and a high maximum output power of 76 mW (from one facet) at room temperature in CW operation. Our shortest wavelength 4.5 μm laser with HR coating reveals a low threshold current density of 1.7 kA/cm2 and maximum output power of 161 mW at room temperature in CW operation. For long wavelength, we present the first room temperature, CW operation of DFB QCL with top grating. The DFB laser emits ~9.6 μm single mode spectra at temperatures between -5 °C and 50 °C. The wide tuning range is obtained to be from 1031 to 1039 cm-1.© (2009) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.