Optical angular momentum interaction with turbulent and scattering media

Optical beams that are structured in both phase and intensity have drawn considerable attention as a promising technology to increase the transmission capacity of communication links. A particular area of application of such beams is over Free-space optical (FSO) links, allowing fiber optical speeds but without the cables. However, the temperature and pressure inhomogeneities in the atmosphere lead to variations of the refractive index along the transmission path, both spatially and temporally, that give rise to a range of distortions to the optical field. In this chapter, we will focus on optical modes that carry Orbital Angular Momentum (OAM) and how they interact with both atmospheric turbulence and scattering media that uniquely distort these specific types of structured optical modes.