Topological scenarios of the creation and annihilation of polarization singularities in nonstationary optical fields

The dynamics of the polarization structure of the speckle field of the photo-induced scattering in LiNbO₃:Fe (unsteady regime) has been analyzed with the use of the methods of the modified Stokes polarimetry. It has been shown that the creation and annihilation of pairs of circularly polarized points (C points) in varying singular elliptically polarized fields proceed via two topological scenarios. It has been found that the creation of pairs of C points is preceded by the appearance of a region where the average ellipticity is larger than the values in the neighboring regions. A similar structure holds after the annihilation of C points.