GROWTH OF LASER OSCILLATIONS AT HIGH EXCITATION

The buildup of single-mode laser oscillations is investigated for the 0.633-µ transition of a helium-neon laser at levels of relative excitation significantly above threshold (1.5 ≤ n ≤ 4) using a fast intra-cavity chopper. The time response agrees with theory. The evolution of the signal provides information on the saturation mechanism and allows a very simple determination of resonator quality, relative excitation, unsaturated gain, and degree of saturation of a laser. The saturation parameter is found to depend on the discharge current. This is attributed to a variation of the gas density in the capillary discharge tube caused by gas heating, which affects the collision-dominated atomic lifetimes. Copyright © 1969 by The Institute of Electrical and Electronics Engineers, Inc.