Experimental verification of fiber-coupling efficiency for satellite-to-ground atmospheric laser downlinks

TLDR

Optical communication offers high capacity for satellite data, but coupling a laser beam to a single‑mode fiber in free‑space links is challenging under atmospheric turbulence. A fast‑steering mirror capable of high‑frequency operation under turbulence was fabricated and its tracking performance verified in real satellite‑to‑ground laser communication experiments. Measured fiber coupling loss of 10–19 dB under turbulence agrees with the predicted 17 dB efficiency.

Abstract

Optical communication is a high-capacity method that can handle considerable satellite data. When common-fiber optical devices such as optical fiber amplifiers based on single mode fibers are used in free-space laser communication systems, the laser beam has to be coupled to a single-mode fiber. Under atmospheric turbulence it would be difficult to make the required fiber coupling efficiency in satellite-to-ground laser propagation paths. A fast-steering mirror that can operate at high frequencies under atmospheric turbulence is fabricated, and its tracking performance is verified in real satellite-to-ground laser communication experiments. The measured fiber coupling loss of 10-19 dB in satellite-to-ground laser communication links under atmospheric turbulence shows good agreement with the predicted fiber coupling efficiency of 17 dB.