THE EFFECT OF KERR NONLINEARITY, DOPPLER BROADENING AND SPONTANEOUS GENERATED COHERENCE ON SLOW LIGHT PROPAGATION

Abstract

The influence of Kerr non-linearity, Doppler Broadening and spontaneous generated coherence (SGC) is presented when a probe light pulse is incident on dispersive atomic medium. We consider different atom-field configura- tions, i.e., N -type electromagnetically induced transparency (EIT), Four- level Λ-type and tripod atomic systems. Initially, we consider a four-level N -type atomic medium and exploited the light pulse propagation through the medium. It is found that the Kerr non-linearity and relaxation rate of forbidden transition affect the dispersive properties of the atomic medium. A more slow group velocity of light pulse propagation is achieved via in- creasing the Kerr field. We also explored the influence of relaxation rate of forbidden decay rate on dispersive properties of the atomic medium. By increasing the atomic number density, the relaxation rate of forbidden de- cay rate increases which leads to control the slow and fast light propagation through the medium. Next, we consider a four-level Λ-type atomic medium and investigated the influence of Kerr non-linearity and Doppler broadening on the dispersive properties of the medium. It is found that the combined effect of Kerr non-linearity and Doppler broadening influence the dispersive properties of the atomic medium more sharply as compared to separate effect of Kerr non-linearity or Doppler broadening. The combined effect of Kerr non-linearity and Doppler broadening on light pulse propagation then leads to a more slow group velocity through the medium. Further, we included the SGC and Kerr non-linearity in four-level atomic system and study the light pulse propagation through the medium. A very steep dispersion is achieved via the combined effect of SGC and Kerr non-linearity. A steep dispersion then leads to more slow group velocity through the medium. Next, we ex- tended our studies to the propagation of light pulse propagation to four level tripod atomic medium via two Kerr nonlinear fields. We expect That a very slow group velocity can be achieved, which in turns leads to stop or halt the light pulse through the medium.