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On the basis of general theoretical results developed previously in [JETP 112, 246 (2011)], we analyze the atomic polarization created by weak monochromatic light in an optically thick, dense, and cold atomic ensemble. We show that the amplitude of the polarization averaged over a uniform random atomic distribution decreases exponentially beyond the boundary regions. The phase of this polarization increases linearly with increasing penetration into the medium. On these grounds, we determine numerically the wavelength of the light in the dense atomic medium, its extinction coefficient, and the complex refractive index and dielectric constant of the medium. The dispersion of the permittivity is investigated for different atomic densities. It is shown that, for dense clouds, the real part of the permittivity is negative in some spectral domains.

This paper demonstrates the use of laser radiation with deep polarization modulation as a method of investigating a magnetically ordered substance. Using a model sample-single-crystal iron borate-as an example, it is shown that this technique can be used to study magnetization processes. A qualitative picture is given of the formation of the polarization-optical response in the sample being magnetized, and the corresponding experimental characteristics are obtained. Sudden changes of the response are recorded that are associated with abrupt reconstruction of the domain structure. The approach thus developed can be useful in studies of the domain structure and of other features of the structure of materials for optoelectronics, nonlinear and magnetooptics, laser engineering, etc.

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Based on the already developed general theory (I.M. Sokolov, D.V. Kupriyanov, and M.D. Havey, JETP 112 (2), 246 (2011)), we have studied the spatial distribution of excited atoms and of the atomic polar ization that a weak monochromatic field creates in a dense ultracold atomic medium. We show that, in the case of a homogeneous random spatial distribution of atoms, the amplitude of atomic polarization averaged over spatial configurations decreases outside boundary regions according to an exponential law, while its phase linearly increases. Based on this, we have numerically determined the extinction coefficient and the light wavelength in the medium, as well as its dielectric permittivity. The dispersion of the permittivity at dif ferent concentrations has been studied. We show that, for dense clouds, the real part of the dielectric permit tivity acquires negative values in a certain frequency range. Based on the calculation of the spatial distribution of excited atoms, we have analyzed the character of the transfer and trapping of quasi resonant radiation in atomic clouds of differing density.