Helium-neon laser for carbon dioxide gas analysis

This paper reports on the development of a He-Ne laser that lases on the 3s2-3p1 transition of neon with a wavelength of 4.2 microns, which is strongly absorbed by CO2, and has an output power of 2.8 mW. Lasing on two competitive transitions with wavelengths of 3.3922 and 3.3912 microns is suppressed by means of a methane-filled intracavity cell. The probabilities of emission and absorption at the lasing frequency are calculated for a two-level system in the case of different lasing-level degeneracies; interlevel relaxation is taken into account. A comparative analysis of the parameters of the 3s2-3p1 and (competitive) 3s2-3p4 laser transitions is performed on the basis of the computational results and experimental data.