RADIATION AND PRESSURE BROADENING TECHNIQUE FOR SINGLE FREQUENCY GAS LASERS

Single frequency operation is achieved in a gas laser by mutually adapting the total gas pressure and the radiation density so that twice the radiation-broadened homogeneous linewidth is greater than the inhomogeneous linewidth. Such lasers typically employ high pressures (e.g., 8-10 Torr in He-Ne) and narrow bore waveguide tubes (e.g., 0.4 mm). Other configurations for increasing radiation density described include the use of relatively larger diameter gas tubes in various types of confocal resonators, and/or a plurality of such gas tubes disposed along a zig-zag path within a free space resonator.