How Satellites Use Lasers and Colors to Send Data Fast

This patent describes a satellite communication system that uses two low-orbit satellites linked by a high-speed laser beam, which splits light into different colors to send massive amounts of data quickly between ground stations or aircraft.

What it covers

The patent describes a communication system using two satellites in low or medium Earth orbit (LEO/MEO) to relay data. A first satellite talks to a ground station or an aircraft (a "first transceiver" per claim 1 and 2) using a radio or laser link (claim 14). This first satellite then sends data to a second satellite using a special "laser communication crosslink" (claim 1). This laser link is very fast because it uses "wavelength division multiplexing" (WDM), meaning it sends data on multiple different colors of light at the same time (claim 1). The second satellite then sends the data down to another ground station (a "second transceiver" per claim 1 and 5). For example, an unmanned aerial vehicle (UAV) could send surveillance data to a first satellite, which beams it via laser to a second satellite, which then sends it to a ground control station in near real-time (claims 4, 8, 9).

What it doesn't cover

• —Communication systems where satellites are only linked by radio frequency (RF) signals, as it specifically requires a "laser communication crosslink" (claim 1).
• —Laser communication crosslinks that do not use "wavelength division multiplexing" (WDM) to increase data rate (claim 1).
• —Satellite systems where both satellites are in geostationary orbit, as it specifies LEO or MEO below 36,000 km (abstract).
• —Systems where the satellites cannot autonomously compute a data route, as claim 16 describes this as an optional feature.
• —Systems that do not achieve low latency (less than 100 ms) or high data rates (greater than 1 gigabit per second) as specified in claims 9, 10, and 11.

The clever bit

The novelty lies in combining low-Earth orbit satellites with high-bandwidth laser communication crosslinks that specifically use wavelength division multiplexing. This allows for extremely fast, secure data transfer between satellites, overcoming the limitations of traditional radio links and enabling rapid relay from mobile platforms to ground stations.

Why it matters

This patent from Raytheon focuses on creating a robust, high-speed communication network for applications requiring fast data transfer, particularly for military or intelligence operations involving airborne assets like UAVs. The use of laser crosslinks and WDM allows for much higher bandwidth and lower latency than traditional radio frequency satellite links. This technology is foundational for secure, real-time data relay in challenging environments, supporting critical missions.

Real-world examples

• 1.Starlink's inter-satellite laser links
• 2.Project Kuiper's planned inter-satellite laser links
• 3.Military secure data relay networks
• 4.High-bandwidth communication for unmanned aerial vehicles (UAVs)