Characterization of pointing and tracking performance in varying turbulence across the Chesapeake Bay

Abstract

Free space optical communication (FSOC) systems’ performances are highly dependent upon their ability to quickly, accurately, and precisely point and track targets. In addition to fundamental geometric limitations, pointing and tracking (PAT) challenges are exacerbated in atmospheric links due to atmospheric turbulence effects imparting variability in the optical propagation path. In this work we present the design, characterization, and field demonstration of a fixed-link PAT system utilizing a fast-steering-mirror (FSM) based optical transmitter and a quadrant photodetector (QPD)-based optical receiver. We describe the fundamentals of quick, low complexity spiral scan acquisition and perturb-and-observe tracking algorithms. The system is integrated into the Naval Research Laboratory’s (NRL) 16km maritime FSOC testbed across the Chesapeake Bay and the operational speed and reliability of the system is reported. This system presents a simple, low SWaP-C solution for challenging atmospheric FSOC environments.