Two-dimensional simulation of an unstable resonator with a stable core

An optical resonator simulation code based on the idea of a partially coher ent optical field has been developed and used to optimize the design parame ters of an unstable resonator with a stable core. The resonator was intende d for use with low-gain, large-bore lasers, such as the chemical oxygen-iod ine laser (COIL). First the design parameters of the resonator were optimiz ed by the simulation code; then a set of mirrors was fabricated for a small -scale COIL. A 14-W output with M-2 = 29 was obtained. The experimentally o btained results were in good agreement with calculations. (C) 1999 Optical Society of America.