General Atomics Aeronautical Systems, Inc. (GA-ASI) has completed an air-to-air laser communication link between two company-owned King Air aircraft equipped with Laser Airborne Communication (LAC) terminals from GA-ASI. Due to its Low Probability of Interception/Low Probability of Detection (LPI/LPD) and anti-jam capability, which may handle far larger data rates than radio frequency systems, laser communication is attractive for military purposes.
On September 26, 2022, the plane took off from Montgomery Field in Kearny Mesa, California, and conducted the test in a separate airspace area close to Yuma, Arizona. To exchange data, including real-time navigation, video, and speech data, the crew maintained a link at 1.0 Gigabits per second (Gbps) during the flight test.
According to Satish Krishnan, vice president of mission payloads & exploitation at GA-ASI, this air-to-air demonstration was a great success and a significant turning point for the Lasercom development team. According to him, if this flight is a success, there will be more chances to show off crosslinks between aeroplanes and other platforms, including unmanned aircraft, ships, and space systems.
To make these capabilities available to users in a range of domains, from the air to the sea, GA-ASI has created a family of optical communication capabilities. GA-ASI envisions that beyond-line-of-sight communications for airborne, maritime, and ground users who also use optical communications, as well as with future air-to-space optical communication applications, will be possible with Remotely Piloted Aircraft (RPA) made by the company thanks to laser communications. The MQ-9B SkyGuardian/SeaGuardian, MQ-9A Reaper, and MQ-1C Gray Eagle 25M unmanned aircraft from GA-ASI may all use this functionality as a podded option.
GA-ASI tests come much ahead of the USAF AFWERX programme, which aims to develop an airborne laser communication system for aircraft space communications that can also be used in other modes like air to air.
What is laser air to air communication?
Free space optics (FSO) communication uses laser or optical beams that have been changed to send information through the air. The idea of FSO light communication was introduced more than a century back. In his 1880 photophone patent, Alexander Graham Bell showed how an intensity-modulated optical beam (sunlight) could be used to send phone signals 200 m through the air to a distant receiver.
Airlines are now providing their consumers with an internet connection similar to Fiber to the home (FTTH), in-flight entertainment, mobile services, Wi-Fi, and the Internet of Things. Aircraft also share a lot of safety and navigation data, for example, for equipment monitoring and in-flight maintenance, in addition to the needs of passengers.
The installation of high-speed wireless links to and from the aircraft is necessary due to the increase in throughput brought on by these new uses. The only technology that can deliver the throughput of more than 10 Gb/s required for 500 people on an A380 to stream a series in Ultra HD is free space optical communication technology, also known as laser communication.
Laser communication is being extensively researched for its military uses, such as drones or spy planes communicating with ground stations in great detail.
The very high-speed telecommunications networks, which presently rely on static fibre-optic systems, can be extended to any location on the planet, even in orbit, thanks to laser communication’s capacity to connect constellations of satellites, balloons, drones, and aircraft to ground stations.
Unfortunately, atmospheric turbulence still restricts this technique. The air’s turbulence and inhomogeneity reduce the beam’s power and alter its wavefront. As a result, the link has a constrained range and speed. Although wavefront correction systems exist, they call for active optomechanical parts that are challenging to install, for instance, in aircraft.
United States Air Force’s AFWERX program
The 2022 US Air Force’s AFWERX programme is paying for the development of a pod that will allow laser communications between aircraft and satellites in orbit even when there is no line of sight.
If this AFWERX-funded programme can make a laser communications pod that works and can be put on existing planes, it could make it easier to put similar systems on both manned and unmanned planes and other platforms that can act as sensor relays.
This idea could be combined with high-altitude platforms to provide incredibly reliable beyond-line-of-sight communication relay capabilities for many other aircraft operating within line-of-sight, such as stealthy swarms of aircraft or weapons, even during a peer-state conflict with a lot of electronic warfare capabilities.
In January, AFWERX gave Space Micro, a San Diego company that makes satellite sensors, software subsystems, and communication technologies, a Phase 1 Small Business Technology Transfer contract. Space Micro is working on a project called DEFORMO. Their goal is to make an “Air-to-Space Laser Communications Pod” that can be used on different types of USAF aircraft.