Nonlinear magneto optical effects in alkali atom vapour
Prof. Dr. Marcis Auzins (University of Latvia, Lettland)

When coherent radiation excites an atomic system Zeeman coherences can be created among the magnetic sublevels of atomic states. At low laser intensity, coherences appear in the excited state of the atom. As the laser intensity increases, the absorption processes become nonlinear and coherences are created among the magnetic sublevels of the ground state as well. These coherences can substantially change the optical properties of gas. For example, decrease (dark states) or increase (bright states) substantially the ability of gas to absorb the resonance radiation. When the degeneracy among the magnetic sublevels is lifted by applying an external field — electric of magnetic, the coherences are destroyed. As a result, nonlinear magneto-optical resonances can be observed in the laser-induced fluorescence. In the Laser Centre of the University of Latvia we have developed theoretical model that allows to analyse these resonances in a great detail, as well studied extensively magneto optical resonances in alkali vapour contained in an ordinary glass cell as well in the extremely thin cells, when separation between cell walls can be substantially smaller than the wavelength of the excitation laser radiation. Results of these studies will be presented in the talk.