EFFECTS OF COLLISIONS ON SATURATION BEHAVIOR OF 6328 A TRANSITION OF NE STUDIED WITH A HE-NE LASER

The power output of a single-mode 6328 He-Ne laser is studied as a function of cavity tuning and for different values of gas pressure. A theory due to Szöke and Javan is used to interpret the results. Two parameters γ and γ′, which characterize a homogeneous line shape in the atomic polarization to third order, are determined as a function of the total pressure P. The results for two different gas mixtures are as follows (in units of MHz/Torr): dγdP=22±7 and dγ′dP=58±13 for an 8:1 He3-Ne20 mixture; dγdP=12±4 and dγ′dP=39±9 for a 5.5:1 He3-Ne22 mixture. Linear extrapolation of γ and γ′ to zero pressure yields the radiative linewidth γN=13±12 MHz. An asymmetry Δ in the frequency dependence of the power output is determined as a function of P, with the result that dΔdP=2.3±0.6 MHz/Torr. The shift of the minimum of the power dip is toward increasing frequency for both mixtures. © 1969 The American Physical Society.