Influence of gas pressure in arc lamps on the pumping efficiency of CW garnet lasers

A study was made of the influence of the gas pressure in xenon and krypton arc lamps on the pumping efficiency of yttrium aluminum garnet (YAG:Nd³⁺) lasers. The pumping efficiency was deduced from the laser efficiency achieved at a constant output power. An increase in pressure in a cold lamp from 1 to 10 atm increased the laser output power by a factor of 1.6 if the pumping was provided by krypton lamps, and by a factor of 1.2 when xenon lamps were used. The rise of the efficiency of the xenon lamps with increasing pressure was observed only up to 3 atm. The results obtained were explained by considering the influence of pressure on the intensity of the continuum and those emission lines in the pumping radiation whose wavelengths were located within the absorption bands of YAGrNd³⁺. When the pressure was optimal, the pumping efficiency of the krypton lamps was, on the average, 1.8 times higher than the corresponding efficiency of the xenon lamps. The addition of xenon to the krypton lamps gave no advantages over the lamps filled with pure krypton.