Experimental analysis of orbital angular momentum-carrying beams in turbulence

Abstract

In a laboratory experiment we generate, propagate, and detect laser vortex beams carrying orbital angular momentum (OAM) by means of spatial light modulators (SLMs). We show that beams with OAM states from -20 to +20 can be effectively generated using different types of phase gratings, and that excellent contrast between adjacent OAM modes is achieved. A weak turbulent air flow is induced on the propagation path to emulate the effects of atmospheric turbulence. By characterizing the effects of optical turbulence on the modal crosstalk among received OAM states we show that it is possible to distinguish them for the purpose of increasing the data throughput of a laser communication link in weak turbulence. It is also demonstrated that by increasing the complexity of the receiver, optical separation of the OAM modes is possible at stronger turbulence conditions.