Degradation of light carrying orbital angular momentum by ballistic scattering

Abstract

Structured light can enhance the functionality of optical communication and sensing systems. Dense scattering environments such as those experienced in coastal water and foggy conditions result in degradation of structured optical fields. We present findings that characterize the degradation of the phase structure of ballistic scattered light carrying orbital angular momentum (OAM) propagated through a dense scattering medium over distances of up to 20 m. We present a numerical channel modeling approach that can predict the scattering behavior at extended distances, which indicates that there is a strong mode-dependent variance in cross talk from the interaction of beams that carry OAM with randomly displaced scattering particles. These results present an effect that could allow the use of OAM modes to enhance particulate size sensors and could potentially lead to the development of novel tools for monitoring particles in underwater or free-space optical channels.