Negative branch hybrid resonator for COIL

Abstract

A rectangular negative branch off-axis hybrid resonator was coupled to a 10-kW class Chemical Oxygen-Iodine Laser (COIL). Various schemes of geometrical coupling between resonator and gain medium were investigated. The extracted power was 6.6 kW and reached about 70% of the output power for the COIL device in an optimized conventional stable resonator configuration. Experimentally measured margins for the sensitivity of resonator setup and alignment were found in close agreement with numerical calculations. Power density distributions were measured in the near field and in the far field. The divergence of the emitted laser beam in the unstable direction was lower than 2 times diffraction limited.