Wirelessly transmitting large volumes of information at high data rates underwater is becoming increasingly important for such applications as environmental monitoring and petroleum exploration and maintenance. Underwater free-space optical (FSO) communication addresses the aforementioned need by providing wireless high-data-rate links. Visible light transmission through seawater typically peaks in the blue-green spectrum (475 nm–575 nm), but local clarity conditions, which are dynamic, strongly influence the actual maximum. We describe the development of a new laser-wavelength auto-selection algorithm and system for optimized underwater FSO communication. This system has the potential to improve underwater optical link reliability for high-data-rate communications. First, we describe the laser system and water tube setup for performing optical experiments. Next, we present research on recreating various seawater types (from clear to turbid) in the laboratory using particle suspensions and dye, which will enable wavelength-dependent transmission tests. Finally, we show experimental results from optical water tube tests, and describe the development of the autoselection algorithm.

Date Published: 7 October 2014
PDF: 8 pages
Proc. SPIE 9224, Laser Communication and Propagation through the Atmosphere and Oceans III, 922417 (7 October 2014); doi: 10.1117/12.2063328

Published in SPIE Proceedings Vol. 9224:
Laser Communication and Propagation through the Atmosphere and Oceans III
Alexander M. J. van Eijk; Christopher C. Davis; Stephen M. Hammel, Editor(s)