Hannover 2016 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 58: Poster: Quantum Optics and Photonics IV

Q 58.43: Poster

Donnerstag, 3. März 2016, 16:30–19:00, Empore Lichthof

Edge diffraction of optical-vortex beams formed by means of a "fork" hologram — Aleksey Chernykh¹, Aleksandr Bekshaev², and •Anna Khoroshun¹ — ¹East Ukrainian National University, Severodonetsk, Ukraine — ²I.I. Mechnikov National University, Odessa, Ukraine

We present experimental and numerical studies of a transverse profile for a beam obtained by the screen-edge diffraction of optical-vortex (OV) Kummer beams with different topological charges generated by means of a "fork" hologram. Our main results concern the behavior of secondary OVs formed in the diffracted beam due to splitting of the incident multi-charged OV into a set of single-charged ones. When the screen edge moves across the incident beam, OVs in every cross section of the diffracted beam describe complicated spiral-like trajectories which distinctly manifest the screw-like nature and the energy circulation in the OV beam. The trajectories contain fine structure details that reflect the nature and peculiar spatial configuration of the diffracting beam. For the Kummer beams’ diffraction, the trajectories contain self-crossings and regions of "backward" rotation (loops). In the case of Laguerre-Gaussian beams, the trajectories are smoother. At certain conditions, positions of separate OVs as well as their mutual configuration (a singular skeleton of the diffracted beam) demonstrate high sensitivity to the screen edge dislocation with respect to the incident beam axis. This effect can be used for remote measurements of small displacements and deformations.