| Abstract [eng] |
This research work aims to analyze light propagation in resonant cold atomic gas enviroment. When weak probe field propagates through such a medium, coherently preparated by strong control field, the electromagnetically induced transparency is observed. In theoretical model under adiabatic approximation the absorption of probe field under resonance is totally eliminated. However non-adiabatic correction provides the absorption of probe field. This absorption also changes the form of propagating probe pulse. In the I part of reseach we derivered equation for slowly varying plobe light amplitude including second order non-adiabatic correction. Using the equation we get probe pulse form when initial puls is gaussian. There was found that for the higher width of initial pulse, the absorbtion, spread and deformatation of propagating pulse is smaller. By turning off the control field the probe can be stored in spin exitation of the atoms. By turning on the control field the probe can be restored. During this prosess the deformation of probe field due to absorbtion is significant when propagation direction is changed. In the II part we get the same probe pulse when propagation direction is changed after stopping it. There was found that this way pulse is deformated more than in the I part if it fitted in the medium during the stopping. In the III part there was investigated propagation of adiabatons when probe and coupling pulses have comparable strength. There was prpposed different method of solution to get propagation equations of adiabatons. Using initial probe field as gassian and constant control field we get numerical and analytical results which mach perfectly to each other and to other authors work. |
