Experimentally evaluating beam scintillation and vortex structure as a function of topological charge in underwater optical turbulence

Abstract

Optical communication links constructed using orthogonal basis beams have the potential to significantly increase data bandwidth through the use of a complex set of alphabet symbols decoded at the receiver by a machine learning-based classifier. Vortex beams theoretically have the capability to mitigate some of the deleterious effects of optical turbulence. Our research objective is to study Laguerre–Gaussian (LG) single mode basis beams under the assumption that the superimposed beams will maintain a more robust vortex structure on propagation through optical turbulence. If the vortex structure is preserved then the feature diversity of the symbols will allow effective machine learning classification. To better understand the primary drivers influencing vortex robustness, we experimentally measured the scintillation and vortex structure of zero-order LG beams through strong underwater optical turbulence as a function of topological charge ranging from one to nine. We conclude that LG beams with higher topological charges appear to distort less upon propagation, suggesting their suitability as basis beams for easier classification by machine learning techniques.