Free space optical communications based on Quantum Cascade Lasers

Free space optical (FSO) communications are a potential application envisioned for Quantum Cascade Lasers technology. In this paper, we sketch out the main market scenarii for FSO communications, where data channels should reach up to Tbit/s over distances that range from 0.1 to 36000 km. We analyze where QCLs can be relevant, and what standards they must meet to be relevant at the industrial level. The following topics are discussed: competing technologies, atmospheric transmission physics, signal processing and multiplexing. We try and translate the constraints of the system-level into challenges for device-level research and development.