VIBRATIONAL COOLING OF THE ACTIVE MEDIUM OF A CO2-LASER BY THE INTRACAVITY RADIATION FLUX

We report, we believe for the first time, experimental values of the r otational and vibrational temperatures of CO2 in an operative laser. T he device under study is a DC-excited fast-axial-flow CO2 laser and ca n be viewed as a scaled down version of an industrial laser for cuttin g and welding. The gas inlet section is optimized for gain symmetry. T he laser operates at a maximal electro-optic efficiency of 26%, reachi ng 1 kW m(-1) output from a 19 mm bore discharge at 24%. An infrared t uneable diode laser spectrometer was adapted to allow transverse probi ng of the discharge. The results show the significant cooling effect o f the intra-cavity radiation intensity on the CO2 vibrational modes, a nd the observed gas temperature drop associated with the extraction of laser power is consistent with the mass flow through the discharge.