High-power optically pumped CW 12 µm NH3amplifier systems

A theoretical and experimental study of a CW CO2laser pumped Raman NH3amplifier at 12 μm is presented. Experimentally we demonstrate an amplifier power conversion efficiency of 30 percent, which is the highest reported to date for any optically pumped system in this spectral range. An amplifier model based on the density matrix treatment for a near-resonant Raman interaction was found to give a good description of the experimental behavior when thermal effects such as density gradients were also included. Scaling relations for the amplifier are deduced and used to illustrate the conditions for which one might achieve a 150 W continuous wave output.