Effects of near-resonance self-absorption on CO laser kinetic modeling

Resonance self-absorption from overlapping lines is an important pressure-dependent mechanism for theoretical analysis of a high-pressure CO laser. Although the effect on total optical output efficiency, kinetic heating rate, and transient time scales is small, predicted output spectral distributions can change significantly. Results of calculations will be presented which show that output power is redistributed to higher vibrational bands with more unique P(J) characteristics. Previous analytical work on CO laser kinetics produced distributions that lay one or two nu bands lower than what is observed, and was incapable of explaining anomalous spectra which often show certain transitions missing. Qualitative comparisons with experiment indicate that these effects occur at much lower pressures than theoretically predicted by this analysis. This suggests that further work will be required to correctly describe the mechanism of optical broadening in a CO laser medium.