Abstract

Unstable resonators with output mirrors of Gaussian or super-Gaussian radial reflectivity profiles provide wide filling of the active material without paying in beam quality as with traditional unstable resonators with totally reflecting (hard edge) output couplers. These features allow high power extraction with low output beam divergence. Unstable resonators with radially variable mirrors were successfully tested with pulsed Nd: YAC^1.2 and CO₂ TEA³ high energy lasers. It is therefore of great interest to access the applicability of these resonators to high-power cw lasers stich as the multi-kilowatt CO₂ lasers used in material working. As an alternative approach, hard-edge phase unifying mirrors have been proposed and experimentally demonstrated for cw high power CO₂ lasers.⁴

© 1991 Optical Society of America