Experimental Demonstration of Adaptive-Optics-Based Turbulence Mitigation in a Mode-Multiplexed Free-Space Optical Link by Using both Radial and Azimuthal Spatial Indices

We experimentally demonstrate turbulence mitigation by adaptive optics for a 400-Gbit/s free-space link multiplexing four Laguerre Gaussian modes using both radial and azimuthal indices. The turbulence-induced power loss and crosstalk are reduced by ~10 dB and ~18 dB, respectively.