Adaptive-waist modes for free-space optical communications

Free-space optical communication systems are vulnerable to phase distortions and amplitude fluctuations caused by atmospheric turbulence, which degrade signal coherence and impair overall performance. Instead of correcting these distortions in real time, we propose an approach based on adaptive-waist modes statistically matched to the turbulence, assuming the transmitter has access to turbulence statistics but not to instantaneous atmospheric conditions. A fundamental Gaussian adaptive-waist mode maximizes power efficiency, while distributing power across multiple adaptive modes enhances link reliability by mitigating turbulence-induced fading. This tradeoff is quantitatively evaluated under varying turbulence conditions, demonstrating significant performance gains over standard Gaussian beams without requiring wavefront correction.