Beam-propagation numerical studies in three-level absorbers: nontrivial induced lenses and their spectral manifestations

摘要

The numerical simulations of two coaxial laser beams, pump and probe, propagating in a three-level absorber are presented. The fixed-pump beam frequency and the variable-probe beam frequency are near-resonant to the adjacent transitions. Depending on the ratio of the population relaxation rates, either absorption or amplification of the probe field may occur, both demonstrating symmetric Rabi-splitted spectra of the absorption coefficient if the on-resonance pump intensity is high enough. In contrary to this, the spectra of the probe beam transmitted intensity are shown to be asymmetric due to the frequency-sensitive saturated refraction induced by the pump beam. The competition of level population changes and Rabi splitting is shown to cause the nontrivial induced lenses responsible for the complicated dependence of spectral asymmetry upon the pump intensity.