Gain dynamics in a pulsed laser amplifier on CO – He, CO – N2 and CO – O2 gas mixtures

Small-signal gain (SSG) dynamics G(t) in the active medium of a pulsed laser amplifier operating on the v + 1→vP(J) vibrational – rotational transitions of the CO molecule, including high (v > 15) vibrational transitions, is studied experimentally. It is demonstrated that as the vibrational number increases from 7 to 31, G changes with time slower, while G_max decreases in this case by three times. It is found that at a fixed value of v the rate of the SSG rise increases with increasing the rotational number J > 6. It is shown that in oxygen-containing gas mixtures (CO:O₂ = 1:19) the value of G_max at low vibrational levels (for v < 13) can substantially exceed G_max in mixtures containing nitrogen (CO:N₂ = 1:19) instead of oxygen. It is found that the efficiency (47%) of a CO laser on mixtures with a high concentration of oxygen considerably exceeds the efficiency (30%) of a CO laser operating on a nitrogen-containing mixture.