Abstract:
Experiments on excitation of meridional rays and optical vortices in short silica-polymer optical fibers were carried out using a laser ($\lambda$ = 532 nm) and lenses with different numerical aperture values. For research, we have drawn out samples of optical fibers with a core diameter of 200–800 $\mu$ microns and a reflective shell made of various polymers. In experiments, under different excitation conditions, radiation intensity distributions were recorded at the output end of the optical fiber (in the near field) and in the far field. Caustic control allowed to excite different groups of optical vortices in and observe various topologies of intermode interference, including spiral structures. A qualitative analysis of the experimental results was carried out.
Keywords:multimode optical fiber, radiation intensity distributions in near and far fields, optical vortices, caustics, intermode interference.