Recent experiments have demonstrated a significant power loss (as great as 50%) from the central far-field spot of a pulsed CO2 electric-discharge laser. Our theory shows that saturation effects that follow the unstable resonator mode variations can create index variations. These index variations lead to a phase grating, and power losses result from diffraction off the grating.
Gregory C. Dente,
"Phase Grating Effects In Pulsed CO2 Electric Discharge Lasers", Proc. SPIE 0293, Wavefront Distortions in Power Optics, (30 December 1981); doi: 10.1117/12.932337; https://doi.org/10.1117/12.932337