Soliton-like topological defects in transverse polarization patterns emitted by broad-area vertical-cavity surface-emitting laser

Vertical-cavity surface-emitting lasers (VCSEL) have a strong tendency to emit space modulated states in the form of high order modes. These lasers show a beautiful example of the self organization phenomena in a nonlinear optical system. Due to symmetry the breaking of some localized structures in the output laser beam can be observed. Certain structures are of interest due to their potential for information encoding and processing. Addressable soliton-like excitations might lead to new forms of all optical, massively parallel information processing. In this present paper, as a first step, we introduce a general definition of vector topological defects by an analogy with the topological solitons in ferromagnets. To describe the complex polarization pattern we use only one complex function w(z), which is the homographic function connected with the Stokes parameter of the field. The application of the developed method to the analysis of the results of numerical simulation of the index-guided VCSEL is presented.