Key technologies and development trends of ultra-high-speed atmospheric laser communication

Free-space optical communication is a wireless communication technology that can build point-to-point ultra-high-speed laser communication links without relying on optical fibers. Among them, atmospheric laser communication, which uses the atmosphere as the transmission medium, has many advantages such as flexibility, high speed, strong anti-electromagnetic interference capability, high confidentiality, and no spectrum restrictions, so it has attracted more and more attention. Atmospheric laser communication can be categorized by application scenarios into: Satellite-to-Air, Satellite-to-Ground, Ground-to-Air, Ground-to-Ground (including indoor FSO), and Air-to-Air laser communications. This article introduces the key technologies used in ultra-high-speed atmospheric laser communication, including acquisition, tracking, and pointing technology (ATP), adaptive optics technology (AO), hybrid FSO/RF communication technology, and reconfigurable intelligent surface technology (RIS), etc., and analyzes the factors affecting ultra-high-speed atmospheric laser communication such as atmospheric turbulence. It is foreseeable that in the future, ultra-high-speed atmospheric laser communication will be closely integrated with radio-frequency communication to achieve a more high-speed, more stable and more intelligent communication network, which will boost civil-military applications such as emergency rescue, smart cities and military communication, and empower the construction of an integrated air-ground-sea space.