Microwave excitation of diffusion-cooled CO2 lasers

The microwave excitation at 2.45 GHz of diffusion cooled CO2 lasers is investigated. Two different planar discharge channel geometries were used. Of the two laser systems, the former (50 cm active length, with a 1.9 × 20 mm channel cross-section) obtained a laser output power of 16.9 W. This value increases to 22 W or by 30% with an addition of 5% xenon to the gas mixture of He:N2:CO2 = 60:20:20. Measurements of the small signal gain and the saturation intensity show that this effect is attributed to an increase of the small signal gain whereas the saturation intensity remains fairly constant. With a second laser system, 50 cm long as well but a 1.4 × 32 mm cross-section, a laser power of 35 W could be reached without xenon.