Nonlinear reflection of laser beam from high density atomic vapor

Abstract

We have investigated the nonlinear selective reflection of a laser beam (λ = 780 nm) from a high density rubidium vapor. The laser frequency was tuned over atomic transitions and coherent optical excitation of the atomic vapor was realized. The observed narrowing of reflection spectral profile is associated with a competition of two nonlinear processes: optical field induced coherent broadening (Rabi broadening) and optical saturation induced decreasing of dipole–dipole broadening of atomic transitions. For more complete understanding the spectral narrowing we suggest to perform a set of new experiments.