Mode Correlation of Mode Diversity Free Space Optical Systems Under Atmospheric Turbulence

We have explored the mode correlation by simulating the process of free-space optical communication with mode diversity. Our results show that the correlations are different between each pair of modes.
$LP_{11}$
and
$LP_{21}$
maintain a positive correlation, while the rest of the modes are negatively correlated with each other. For variations in transmission conditions, both turbulence intensity, aperture diameter, temporal correlation and inner-outer scale effect have influence on mode correlation.