Self-defocusing of light by adiabatic following in rubidium vapor

The narrow-line output of a dye laser on the low-frequency side of the P122 resonance line (7948 ) of rubidium was self-defocused by passage through dilute rubidium vapor. The defocusing was caused by the electronic nonlinearity associated with "adiabatic following" of the laser field by the pseudomoment of the resonant atoms. By using the corresponding nonlinear dielectric constant, the wave equation was solved numerically and gave excellent quantitative agreement with experiment. © 1972 The American Physical Society.