Optical Inter Satellite Links for Broadband Networks

Inter Satellite Links (ISL) are essential to connect Satellites operating in a constellation. If these ISLs could manage high data rates in Gigabit per seconds the network becomes a broadband connectivity services. New possibilities for data exchange and independencies from ground networks are offered. LEO satellite constellations with low latency of data streaming, are very attractive as a backhaul infrastructure to connect people worldwide like a Space based Internet or to address Internet of Things (IoT) applications on a global scheme. Optical Inter-Satellite Links (OISL) combine very high data rates with resilient performance. Due to its narrow beam and a coherent detection technology without beacons, these OISLs a very robust. As the optical beams are much narrower than RF beams, no interference with other potential optical communication systems will occur and thus offer high operational security and immunity to interference sources, jamming and eavesdropping. An obvious advantage of the optical ISL is the fact that the frequency usage is not regulated by ITU, which makes the planning and operation of a navigation constellation much easier. OISLs are realized by Laser Communication Terminals (LCT) on each end of the link. The technology readiness of Laser Communication Terminals is TRL9. This paper gives an overview on the current status and on the future developments of Laser communication terminals in the various applications.