Digital sorting of Hermite-Gauss beams: mode spectra and topological charge of a perturbed Laguerre-Gauss beam

Abstract

We developed and implemented an intensity moments technique for measuring amplitude and initial phase spectra, the topological charge (TC) and orbital angular momentum (OAM) of the Laguerre-Gauss (LG) beams decomposed into the basis of Hermite-Gaussian (HG) modes. A rigorous theoretical justification is given for measuring the TC of unperturbed LG beams with different values of radial and azimuthal numbers by means of an astigmatic transformation on a cylindrical lens. We have shown that the measured amplitude and phase spectra of the HG modes make it possible to find the orbital OAM and TC, as well as digitally sorting the HG modes and then restoring the initial singular beam.

Gyrotropic Crystals as a Basis for Creation of Helical Polychromatic Singular Beams

“…The method described in this article can be applied by other researchers to analyze the properties of spin and orbital moments in free space [27,28], to analyze the shapes and properties of beams that carry a topological charge, to study anisotropic media [29,30], and to study the properties of topological charges [31][32][33][34][35][36] both in anisotropic media and in weakly turbulent atmospheric media.…”

Fine Structure of Optical Vortices in Linearly Polarized Laguerre–Gaussian Beams in Oblique Beams Propagating a Uniaxial Crystal

“…The process of annihilation of vortices is typical for the orientation of linear polarization at an angle = γ 45 o , and the process of displacement of vortices is typical for an angle = − γ 45 o . The method described in this article can be applied by other researchers to analyze the properties of spin and orbital moments in free space [26], to analyze the shapes and properties of beams that carry a topological charge, to study anisotropic media [27], and to study the properties of topological charges [28] both in anisotropic media and in weakly turbulent atmospheric media.…”

“…The method described in this article can be applied by other researchers to analyze the properties of spin and orbital moments in free space [26], to analyze the shapes and properties of beams that carry a topological charge, to study anisotropic media [27], and to study the properties of topological charges [28] both in anisotropic media and in weakly turbulent atmospheric media.…”