Super bursts of the orbital angular momentum in astigmatic-invariant structured LG beams

A structured Laguerre-Gaussian (sLG) beam in an opti-cal system with an astigmatic element acquires additional degrees of freedom in the form of changing the fine struc-ture of the beam, its orbital angular momentum (OAM), and topological charge. We have theoretically and experimen-tally revealed that at a certain ratio between the beam waist radius and the focal length of the cylindrical lens, the beam turns into an astigmatic-invariant one, and such a transition does not depend on the beam radial and azimuthal num-bers. Moreover, in the vicinity of the OAM zero, its sharp bursts occur, the magnitude of which significantly exceeds the initial beam OAM and grows rapidly as the radial num-ber increases. (c) 2022 Optica Publishing Group

Automated summary

A structured Laguerre-Gaussian beam in an optical system gains additional degrees of freedom in the form of changing the fine structure of the beam, its orbital angular momentum (OAM), and topological charge. It has been theoretically and experimentally shown that at a certain ratio between the beam waist radius and the focal length of the cylindrical lens, the beam transforms into an astigmatic-invariant one, independent of the beam's radial and azimuthal numbers. Additionally, sharp bursts occur near the OAM zero, with magnitudes significantly exceeding the initial beam's OAM and rapidly increasing with the radial number.