Theoretical and experimental investigations of a stable-unstable resonator applied to chemical oxygen-iodine laser

Unstable resonator with a stable core was developed for Chemical Oxygen-Iodine Laser (COIL). An optical resonator simulation code was developed to optimize the design parameter of the resonator. “Partially coherent optical field” model was employed to handle with multiple transverse mode oscillation. The resonator was successfully oscillated, and a 14 W output with M2=29 was obtained. Theoretically calculated laser output, near-field pattern, and beam quality was in good agreement with experimental results.