  We investigated the spatial distribution of quantum fluctuations in a
squeezed vacuum field, generated via polarization self-rotation (PSR)
interaction of an ensemble of Rb atoms and a strong near-resonant linearly
polarized laser field. We found that the noise suppression is greatly effected
by the transverse profile of a spatial mask, placed in both the squeezed field
and the local oscillator, as well as its position along the focused beam near
the focal point. These observations indicate the spatial multi-mode structure
of the squeezed vacuum field. We have developed a theoretical model that
describes the generation of higher-order Laguerre-Gauss modes as a result of
PSR light-atom interaction. The prediction of this model are in a good
qualitative agreement with the experimental measurements.
