OPTICAL FIELD INDUCED REFRACTIVE INDEX CHANGE DUE TO COLLISION-ENHANCED ZEEMAN COHERENCE

The collision-enhanced Zeeman coherence ρ⁽²⁾ _{(ωl -ω2)} has been demonstrated by the effect of optical field induced index of refraction change, which is described by the real part of the nonlinear susceptibility x⁽³⁾ _{(- ωl，ωl - ω2，ω2)} . The experiments are performed in sodium vapor by a Mach-Zehnder interferometer. The dependences of the effect on the magnetic field, pump beam intensity, and Ar pressure are consistent with the theory.