Orbital Angular Momentum Modulated Free-space Optical Communication systems
The use of orbital angular momentum (OAM) for free-space optical (FSO) communications is almost unexplored. The proposed research will investigate the bit-error rate (BER) performance of FSO systems using OAM. The analysis will begin by considering the ideal case of separable OAM-modulated FSO system performance, to be followed by the individual and combined effects of shot noise, thermal noise, dark current and turbulence. In the presence of turbulence, the separability of OAM signals is no longer maintained, as the inhomogeneities in the refractive index of the air alter the phase structure of the optical vortex. The BER performance of the OAM-based FSO system will be evaluated by considering the effects of realistic OAM crosstalk for various turbulence strength conditions. The research results from this project will be used to help engineers design practical OWC links with higher transmission speed.