RESEARCH INVESTIGATION OF LASER LINE PROFILES
Rept. for 1 Aug 1966-31 Jul 1967
UNITED AIRCRAFT RESEARCH LABS EAST HARTFORD CT
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The objective of this program was to conduct experimental and theoretical investigations of laser line profiles. The broadened homogeneous line width of an argon ion laser was studied as a function of pressure and excitation by means of the Lamb Dip technique. Broadened homogeneous line widths of 200 to 400 MHz were recorded. These line widths are much larger than the 100 MHz radiative line width. The most plausible source for the broadened line is nonradiative phase interruptions occurring from small-angle Coulomb scattering in ion-ion collisions. It is shown that the line width decreases with increasing pressure for a certain range of laser oscillation. A simple collision broadening approach is not applicable to the ion system because of the behavior of the ion density as a function of pressure and excitation. Preliminary experiments were also performed with a CO2-N2-He laser and no experimental indication of a Lamb Dip was found for this laser medium. Some aspects of the theory of a gas laser recently developed by W. E. Lamb, Jr. have been recast in a form which more fully displays the role played by the particle dynamics. It is shown that effects due to long range forces are most noticeable at long optical wavelengths and when there is a large difference between the lifetimes of the two-laser levels.
- Lasers and Masers