Optical Pumping Theory in Polarization Spectroscopy of Na

Abstract

The aim of this paper is to present detailed theory of polarization spectroscopy of Na in the case of a slow relaxation rate of a lower state involved in a resonant transition. An interpretation of the signal in such a polarization spectroscopy is given by combining the theory of birefringence and dichroism with a first-order theory of velocity-selective optical pumping in a four-level system. Because of the high multiplicity of Zeeman levels, the signal is complicated by the occurrence of cross-over resonances in addition to the principal resonances. This interpretation is in good agreement with the experimental results which have been already published about the Na D₁ line.