Characterization of Orbital Angular Momentum-Multiplexed FSO Channel in the Presence of Pointing Errors

Free space optical communication (FSO) uses laser transmitters at near-infrared wavelengths for line-of-sight wireless communication. Through the use of advanced laser beams instead of the conventional Gaussian-shaped beam, orbital angular momentum (OAM) allows taking advantage of higher degrees of freedom in the FSO link design. OAM enables the simultaneous transmission of multiple data streams due to the orthogonality between beams of different spatial modes. However, in practice, atmospheric turbulence and pointing errors may destroy the orthogonality. Pointing errors may result in crosstalk between modes and power disparities as a result of shifting the received beam. In this paper, we consider Laguerre-Gaussian beams and investigate the effect of random pointing errors on crosstalk coefficients.