Slow Light in Polymer Film with Narrow Dip in the Absorption Spectrum

吕毅 Lü Yi, 吴九汇 Wu Jiuhui, 李丽丽 Li Lili

David Petrosyan, Yu. P. Malakyan

We examine the effect of electromagnetically induced transparency in a thin cell filled with a vapor of three-level $\ensuremath{\Lambda}$ atoms. We show that the absorption spectrum of the probe field and the fluorescence signal from the upper atomic level contain two sub-Doppler dips that have considerably different widths. The narrow dip corresponds to the effect of electromagnetically induced transparency, whereas the broader one results from the optical pumping of the external atomic states. Under the condition of exact resonance of the coupling field with the corresponding atomic transition, these two dips are superimposed on the frequency scale, while in the case of nonzero detuning of the coupling field, the two dips are shifted with respect to each other, which makes it possible to observe a competition between the two effects. In the frequency region where the absorption is low, large optical nonlinearities conditioned merely by the slow atoms having an effective 1 mK temperature are also found.

Divyani Bhagat, Mahesh Krishna Gaikwad

Yuanyuan Li, Xun Hou, Jintao Bai +3 more

This paper investigates the absorptive reduction and the width narrowing of electromagnetically induced transparency (EIT) in a thin vapour film of λ-type atoms confined between two dielectric walls whose thickness is comparable with the wavelength of the probe field. The absorptive lines of the weak probe field exhibit strong reductions and very narrow EIT dips, which mainly results from the velocity slow-down effects and transient behaviour of atoms in a confined system. It is also shown that the lines are modified by the strength of the coupling field and the ratio of L/λ, with L the film thickness and λ the wavelength of the probe field. A simple robust recipe for EIT in a thin medium is achievable in experiment.

Alexander A. Makarov

Absorption spectrum of a system of two closely spaced identical atoms displays, at certain preparation, a dip that can be much narrower than the natural linewidth. This preparation includes (i) application of a strong magnetic field at an angle $\ensuremath{\alpha}$, that is very close to the magic angle ${\ensuremath{\alpha}}_{0}=arccos(1/\sqrt{3})\ensuremath{\approx}{54.7}^{\ensuremath{\circ}}$, with respect to the direction from one atom to another, and (ii) in-plane illumination by a laser light in the form of a nonresonant standing wave polarized at the same angle $\ensuremath{\alpha}$. Both qualitative and quantitative arguments for the narrow dip effect are presented.

Решетов Владимир Александрович, I.V. Meleshko