Experimental study on the effects of OAM beams propagating through atmospheric turbulence

Free-space optical (FSO) communication has gained in interest for a long time due to its ability to have secure transmission and high data rates. Interest has increased in using beams carrying orbital angular momentum (OAM) for FSO communication, due to their (theoretically) infinite number of orthogonal modes and potential high resistance to atmospheric turbulence. In this experimental study, Laguerre-Gaussian (LG) beams are used as OAM beams and LG beam of different orders are generated using a spatial light modulator (SLM). A wave-optics simulation method is used to generate phase screens containing simulated atmospheric turbulence, which in turn are used on two SLMs to generate atmospheric turbulence in our experimental setup. In this study, beams with different orders of OAM are propagated through (simulated) atmospheric turbulence, ranging in strength from weak to strong. The distorted beam is recorded using a CCD camera and the images are processed to determine their spot size, intensity, and (spatial) scintillation index. The effect of the strength of atmospheric turbulence on different orders of LG beams is analyzed using these beam parameters.