Evaluation of a possibility of measuring the topological charge of a vortex beam along an atmospheric path with a Shack-Hartmann sensor
D.S. Rytchkov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: optical vortex, turbulent atmosphere, wavefront, mutual coherence function, Poynting’s vector, optical communication
Abstract
Due to degradation of laser beam properties on atmospheric paths, the maximum length of communication lines is limited. In this regard, it is of interest to evaluate the possibility of detecting the topological charge of a vortex beam disturbed by atmospheric fluctuations using wave front sensors. The problem of measuring the wavefront tilts of a vortex laser beam propagating along a path in a turbulent atmosphere by a Shack-Hartmann sensor is considered. Estimates are obtained for the change in the angles of local tilts of wavefront associated with the solenoidal component of the Poynting vector and the influence of turbulent fluctuations of the refractive index of the atmosphere. Using several specific models of the Shack-Hartmann sensor as an example, the possibility of calculating the value of the topological charge of a vortex Laguerre-Gaussian beam from the measured angles of local wavefront tilts is investigated.
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