  We report that guiding light beams, ranging from continuous beams to
femtosecond pulses, along liquid crystal defect lines can transform them into
vector beams with various polarization profiles. Using Finite Difference Time
Domain numerical solving of Maxwell equations, we confirm that the defect in
the orientational order of the liquid crystal induces a defect in the light
field with twice the winding number of the liquid crystal defect, coupling the
topological invariants of both fields. For example, it is possible to transform
uniformly-polarized light into light with a radial polarization profile. Our
approach also correctly yields a zero-intensity region near the defect core,
which is always present in areas of discontinuous light polarization or phase.
Using circularly polarized incident light, we show that defects with
non-integer winding numbers can be obtained, where topological constants are
preserved by phase vortices, demonstrating coupling between the light's spin,
orbital angular momentum and polarization profile. Further, we find an
ultrafast femtosecond laser pulse travelling along a defect line splits into
multiple intensity regions, again depending on the defect's winding number,
allowing applications in beam steering and filtering. Finally, our approach
describing generation of complex optical fields via coupling with topological
defect lines in optically birefringent nematic fluids can be easily extended to
high-intensity beams that affect nematic ordering.
