Higher-Order Spatial Modes in Turbulence: Alternatives to Orbital Angular Momentum

Abstract

The effect of atmospheric turbulence on Orbital Angular Momentum (OAM) modes, which are a subset of the Laguerre-Gaussian (LG) modes, has been thoroughly studied. Other high-order basis sets such as Hermite-Gaussian (HG, which have a rectangular shape) and Ince-Gaussian modes (which have an elliptical shape) have received relatively little attention. In this work, comparative experimental measurements of low order OAM, Ince-, and Hermite-Gaussian modes in turbulence are presented. It is found that the performance of the mode sets vary dramatically in the same turbulence. Surprisingly, Ince-Gaussian modes experience lower crosstalk and mode dependent loss than LG and HG modes of similar order. This warrants further investigation: could there be an optimal basis set for optical communications in turbulence?