Experimental study on the impact of air turbulence on OAM-based optical links employing local demultiplexing

Orbital Angular Momentum (OAM) beams offer high-dimensional multiplexing capabilities to increase channel capacity in free space optical communication (FSOC) systems. However, challenges to their full exploitation arise in long-distance and deep-space FSOC due to the acquired large beam size exceeding the linear dimensions of the receiver, and the OAM intermodal crosstalk induced by the atmospheric turbulence. In this contribution we study the impact of air turbulence on the local amplitude and phase properties of OAM beams in optical links employing local demultiplexing. We evidence a universal behavior for the local OAM intermodal crosstalk described by a unique master curve of a single dimensionless parameter only. Remarkably, the master curve is independent of the OAM intensity mode pattern and the turbulence structure function. Applications to data transfers from LEO satellites to ground stations (optical downlink) and to OAM entangled photon pairs in quantum communications and information processing are also discussed.