A parametric study of the output of the optically pumped continuous wave CF4 laser

A parametric study of laser output versus CF4 pressure and temperature was performed and correlated with a model for the gain in the system, which includes the relevant relaxation processes. Lasing in CF4 was observed at temperatures below 170 K. Cooling the CF4 gas, the output power of the laser increased from 3 mW at 142 K to 5 mW at 113 K, when 4% of the radiation was coupled out. Chopping the pump, the 16-μm signal consisted of a peak decaying in approximately 2 ms, superimposed on a CW background. This decay is caused by the slow relaxation in the CF4 laser, resulting in filling of the lower laser level. For the CW CF4 laser, vibrational relaxation from the laser lower level is even slower than diffusion to the cold cell walls. To increase the relaxation rate, HD was added. In this molecule, the J=1→3 rotational transition at 447 cm-1 is almost resonant with the ν2 vibration in CF4. Maximum CW output was increased by 25% in a mixture containing 10% HD. At the same time, the lasing pressure range was extended