Coherent reconstruction of turbulence-distorted spatial modes for free-space optical communication

Atmospheric turbulence severely degrades direct single-mode-fiber reception in free-space optical communication by redistributing optical power among spatial modes and inducing deep fades. We propose and experimentally demonstrate a coherent-reconstruction receiver that combines few-mode-fiber collection, multi-plane-light-conversion demultiplexing, and silicon-photonic coherent reconstruction. In laboratory turbulence emulation, both the demultiplexed four-mode power sum and the practical coherent-reconstruction output exhibit lower scintillation than direct single-mode reception. In a 10-Gb/s communication test, the receiver reduces interruption probability and extends uninterrupted communication time by up to 3.02 times. These results establish coherent reconstruction of turbulence-distorted spatial modes as a practical route for mitigating turbulence-induced fading in free-space optical communication receivers.