Pulsed laser operating on the first vibrational overtone of the CO molecule in the 2.5 – 4.2-μm range: 3. The gain and kinetic processes on high vibrational levels

The gain dynamics in the active medium of an overtone CO laser operating on the transitions between high vibrational levels is studied experimentally and theoretically. The gain dynamics is measured on the vibration – rotation transitions of the CO molecule [the P(12) spectral line in the vibrational bands from 20 → 18 to 36 → 34] in CO – He and CO – N₂ laser mixtures. The maximum small-signal gain was 0.43 m^-1. The theoretical model of the CO laser was significantly improved. It was shown that multiquantum and asymmetric VV-exchange processes should be included in the analysis of the population dynamics of high vibrational levels of the CO molecule.