Electromagnetically induced transparency (EIT) effect in a -system formed by Cs atoms line, enclosed in nanometric-thin cells, is studied both experimentally and theoretically for the first time. The atomic column thickness varies in the range of 50–1500 nm. It is demonstrated that when the coupling laser frequency is in exact resonance with the corresponding atomic transition, the parameters of the EIT resonance (also called dark resonance (DR)) depend weakly on , which allows us to detect DR at nm with the contrast of . The obtained DR parameters are the best as compared with those for Rb and lines and Cs line. The DR contrast and width are studied versus laser frequency detunings, coupling laser power, cell thickness, temperature, and applied external magnetic field. The well-resolved splitting of the DR resonance in a magnetic field for nm can be used for magnetometry with high spatial resolution. The theoretical model describes well the observed results.
Nonlinear magneto-optical resonances have been measured in an extremely thin cell (ETC) for the
D1 transition of rubidium in an atomic vapor of natural isotopic composition. All hyperfine transitions of both isotopes have been studied for a wide range of laser power densities, laser detunings, and ETC wall separations. Dark resonances in the laser induced fluorescence (LIF) were observed as expected when the ground-state total angular momentum
Fg was greater than or equal to the excited-state total angular momentum
Fe. Unlike the case of ordinary cells, the width and contrast of dark resonances formed in the ETC dramatically depended on the detuning of the laser from the exact atomic transition. A theoretical model based on the optical Bloch equations was applied to calculate the shapes of the resonance curves. The model, which had been developed previously for ordinary vapor cells, averaged over the contributions from different atomic velocity groups, considered all neighboring hyperfine transitions, took into account the splitting and mixing of magnetic sublevels in an external magnetic field, and included a detailed treatment of the coherence properties of the laser radiation. Such a theoretical approach had successfully described nonlinear magneto-optical resonances in ordinary vapor cells. However, to describe the resonances in the ETC, key parameters such as the ground-state relaxation rate, excited-state relaxation rate, Doppler width, and Rabi frequency had to be modified significantly in accordance with the ETC's unique features. The level of agreement between the measured and calculated resonance curves achieved for the ETC was similar to what could be accomplished for ordinary cells. However, in the case of the ETC, it was necessary to fine-tune parameters such as the background and the Rabi frequency for different transitions, whereas for the ordinary cells, these parameters were identical for all transitions.