Effects of Collisions on Saturation Behavior of the 1.15-μ Transition of Ne Studied with He-Ne Laser

Abstract

The frequency response of the output power of a single-mode He-Ne gas laser has been studied in detail. This has been done in order to obtain information on the effects of atomic collisions on the frequency response of the individual atoms. At the operating pressures, the collision widths were considerably smaller than the Doppler width. From these measurements we find that in addition to pressure-dependent broadening due to hard collisions, there exists appreciable broadening due to soft collisions. Furthermore, we find the atomic collisions lead to an asymmetry in the average frequency response of individual atoms. It is shown that this slight asymmetry of the atomic response leads to a sizable shift of the frequency of the minimum of the Lamb dip where the effect of saturation is maximum. This shift has been obtained and is found to be pressure-dependent.