Compact cw single-mode CO2 : He : N2 lasers with a 1-mm-diam dielectric waveguide discharge tube have exhibited gains of up to 37 dB/m, volumetric power outputs of 15 W/cm3, and saturation parameters of 3600 W/cm2 with a coolant temperature of −70°C. With tap water cooling at 20°C the corresponding values were 24 dB/m, 9.5 W/cm3, and 2100 W/cm2. All of these values are substantially larger than those obtained with conventional CO2 lasers. A 12.5-cm-long waveguide tube with an active volume of 0.096 cm3 gave a power output of 1.4 W at −70°C and 0.9 W at 20°C coolant temperature.