Sending data with lasers, rather than radio frequencies, has the potential to revolutionize the way the military communicates, proponents of the technology have said.
Laser communications, which transmits ones and zeroes in a data stream through narrow beams of energy, is not unlike widely used fiber-optic cable--it just doesn't have the cable.
The military has been looking at "free-space optical communications"--the more technical term--for decades. Several defense contractors, meanwhile, have been investing their own dollars to develop laser communication applications--everything from blue-force tracking in small squads, to links between unmanned aerial vehicles and satellites, as well as communications on the move for ground troops riding in combat or tactical wheeled vehicles.
One vendor said it has already been fielded with a U.S. government customer he could not disclose.
NASA recently began a project to demonstrate how it can use the technology to link Earth-based ground stations to spacecraft traveling millions 01 miles away in the solar system.
Contractors say after years of development, the technology is ready to be widely fielded.
"We're talking data rates that can be 100 to 1,000 times or more greater than what you can get with [radio frequency] data links," said Michael Perry, vice president of the laser-electric optic business unit in General Atomics Aeronautical Systems Inc.'s reconnaissance systems group. The UAV maker is partnering with a German satellite company to demonstrate laser links between a Reaper remotely piloted aircraft and a satellite in geo-stationary orbit some 25,000 miles above the Earth.
The finite amount of radio spectrum available to the U.S. military has been an ongoing issue. At the same time, the demand for it is insatiable. The advent of unmanned aerial vehicles that need to send live, streaming video to bases around the world has driven the high demand, and forced the military to lease time on commercial satellites. The demand is likely to increase as higher resolution, next-generation sensors that require more bandwidth proliferate in the coming years.
The overcrowded airwaves are also prone to interference, or "fratricide" as radio engineers like to call it. Adversaries can also try to intercept messages or jam signals.
Laser communications do not use any of the radio spectrum. And, advocates point out, it is inherently protected. To disrupt a transmission, an enemy would have to be able to detect the narrow beam and find a way to put an object in front of it. To actually intercept data, he would have to place a receiver in its path.
In its simplest form, the energy is transmitted in pulses with the "1" digit being a pulse and the "0" a gap. But modulating the timing can create more sophisticated pulses.
Perry described it as: "Morse code but at ridiculously high rates."
How high? Two gigabytes per second and upwards of 20 gigabytes per second are possible, he said.
Radio frequency transmissions can go to 200 megabytes per second, but 45 megabytes is more typical, said Gary Tarantino, manager of advanced systems and strategic initiatives at ITT Exelis. ITT is working on lasers that can do communications on the move terrestrially between aircraft, ground vehicles and ships.
"You have a tremendous amount of bandwidth that allows you the flexibility to transmit the [intelligence, reconnaissance and surveillance] information in a timely manner," he said.
The downside is that the beams can't bend or penetrate buildings. There must be a line of sight between two points.
"Rain and fog we go through much better than people expect," said Steve Sampson, vice president of advanced programs at Cubic Defense Applications.
Cubic is working on lasers that can do small unit blue-force tracking and tactical communications.
General Atomics, ITT Exelis and Cubic are all betting their own internal research-and-development funds on laser communications. …