Progress in high-speed communication at the NRL Chesapeake Bay lasercomm testbed

The Naval Center for Space Technology at the Naval Research Laboratory has been operating a long-range, maritime, free-space optical communications facility located between Chesapeake Beach, MD and Tilghman, Island, MD. The two sections of the facility are separated by 16.2 km of the Chesapeake Bay. The facility permits one-way communications with the transmitter and receiver at opposite ends as well as double pass communications using a retroreflector array on Tilghman Island and the transmitter and receiver located together at Chesapeake Beach. Over the past year, a ball lens has been incorporated to couple the returned free-space light into an optical fiber. This ball lens makes the coupling much less sensitive to angle. With the lens, averaged coupled power into the receive fiber increased from 50 muW to 130 muW. Link statistics including fade rate and bit error rate are included for a typical summer afternoon for the double pass configuration.