G.V. Bogatirova, A.A. Ch.V. Felde, P.V. Polyanskii, A. Chernyshova, M. S. Soskinc, Polarization Singularities in Partially Coherent Combined Beams//JETP Letters, 2008, Vol. 88, No. 7, pp. 418–422

Vector singularities are predicted and discovered experimentally in partially polarized combined ?elds formed by incoherent superposition of orthogonally polarized beams. Such singularities are U contours with zero degree of polarization and isolated P points with unit degree of polarization centered at vortices of the orthog- onally polarized component of the combined beam. Crossing a U contour switches the polarization state to the orthogonal one. The above-mentioned singularities are adequately described in terms of the complex degree of polarization in the Stokes-space representation. It is shown that the ?eld elements corresponding to the extrema of the complex degree of polarization form the vector skeleton of a partially coherent nonuniformly polarized ?eld.