Radiation self-interaction effects in a cw CO2 amplifier

Three-dimensional numerical calculations made of the radiation parameters of a cw CO₂ amplifier with a circulating active medium. An analysis was carried out of the amplification of Gaussian and annular-profile beams. The calculated energy characteristics of the output radiation showed a satisfactory agreement with the experimental data. The angular divergence of the output beam was 1.5–2 times greater than the diffraction limit because of local temperature inhomogeneities. As a result of self-interaction of the radiation, splitting of the amplified laser beam was possible in the far-field zone. Under selected conditions the upstream angular shift of the output beam did not exceed its divergence.