Fiber-coupling efficiency for free-space optical communication through atmospheric turbulence

TLDR

High‑speed free‑space optical communication systems use fiber‑optic components, but atmospheric turbulence degrades the spatial coherence of the received laser beam, limiting fiber‑coupling efficiency. The study numerically evaluates the fiber‑coupling efficiency of laser light distorted by atmospheric turbulence. The authors perform numerical simulations of laser propagation through turbulence and assess coupling into a single‑mode fiber. The results show that a coherent fiber array with seven subapertures markedly improves fiber‑coupling efficiency.

Abstract

High-speed free-space optical communication systems have recently used fiber-optic components. The received laser beam in such a system must be coupled into a single-mode fiber at the input of the receiver module. However, propagation through atmospheric turbulence degrades the spatial coherence of a laser beam and limits the fiber-coupling efficiency. We numerically evaluate the fiber-coupling efficiency for laser light distorted by atmospheric turbulence. We also investigate the use of a coherent fiber array as a receiver structure and find that a coherent fiber array that consists of seven subapertures would significantly increase the fiber-coupling efficiency.