Hybrid stable-unstable resonators for diffusion-cooled CO2 slab lasers

We present the numerical and experimental study that we carried out to compare the performances of two hybrid stable-unstable resonators for diffusion-cooled CO2 slab lasers. The two resonators are designed to fit a 320 mm x 60 mm x 2 mm rf-discharge channel and are both guided in the narrow transverse direction. They differ in the other transverse direction, consisting of a positive- or a negative-branch unstable resonator scheme. The two solutions have been characterized in terms of modal structure, power extraction, stability, and quality of the extracted beam. (C) 1996 Optical Society of America