Dislocation reactions and topological birefringence of degenerated combined fields of low-mode fiber

Abstract

The results of theoretical and experimental studying of birth and death events and evolution process of degenerated combined mode singularities in low-mode optical fiber are presented in this paper. It is shown, that a topological birefringence phenomenon in a fiber is manifested as the birth, death and metamorphosis events of field singularities and it could be divided into two stages: (1) the wavefield rotation around the optical axis (circular birefringence); (2) the cyclic deformation of the field structure (linear birefringence). To describe the field state at the intermediate fiber cross-section, one was introduced the characteristic surface given by the transversal components of vector Poynting. The wave process flow in this field is characterized by topological reactions of the singular points on the characteristic surface.