ALBUQUERQUE, N.M., 3 Oct. 2008. Three electronics companies are collaborating with the U.S. Air Force to design and demonstrate a 10 gigabit-per-second free-space laser communications link that will be smaller, lighter, and more power-efficient than radio frequency (RF) communications links.
The Air Force Air Force Research Laboratory, Space Vehicles Directorate (AFRL/RV) at Kirtland Air Force Base in Albuquerque, N.M., is collaborating on the project with Discovery Semiconductors Inc. in Ewing, N.J.; Science Applications International Corp. (SAIC) in San Diego; and Schafer Corp. in Albuquerque, N.M.
Team members have demonstrated the 10 gigabit-per-second free space optical communications link, and showed that more than 80 dB of link loss can be overcome with this system, officials say.
"The 10 gigabit-per-second system uses a wavelength of 1550 nanometers where powerful optical amplifiers can be used to boost the transmitted signal and pre-amplify the received signal, says Christoph Wree, the program manager at Discover Semiconductors. "The use of differential phase-shift keying gave us an excellent receiver sensitivity of 27 photons per bit at a bit error ratio of 1e-9. This is only 5 photons away from the quantum limit."
Free-space optical communications links enable the Air Force to increase the data rate and reduce the space, weight, and power consumption with respect to RF comm links. This project demonstrates that the system can overcome large link losses which can be introduced either by ultra long inter-satellite link distances or by link losses arising from atmospheric turbulence.
