Gain Saturation Effects and Beam Symmetrization in Fast-Transverse-Flow Industrial Lasers with Folded Resonators

摘要

Different N-folded multiple-pass resonator schemes were realized and tested in high power fast-transverse-flow CO_2 lasers. In all cases beam ellipticity occur due to gain saturation followed by beam self-action in active medium with fast transverse gas flow. To avoid this effect new resonator structure was proposed where N-folded passes are arranged in different crossed planes declined to the gas flow direction. Fast-transverse-flow industrial CO_2 laser "Lantan" with this resonator scheme demonstrates high beam quality up to 2.5 kW CW output power with differential efficiency of 16%.