The need for ever-increasing data rate communications calls for key enabling wireless technologies, such as Free Space Optical (FSO) communications. There several identified applications for this technology, noteworthy high bit rate point-to-point data transfer, last miles connectivity and, in the space sector, global services using satellites for secure communications. Targeted throughputs range from several Gbps to 100Gbps and above in all weathers and at all times. Indeed, the presence of clouds, haze, rain or turbulence drastically reduces the availability of the communication window particularly at telecom wavelength. Their prospects to provide a solution for this “atmospheric link” of the communication chain may strongly benefit to be seconded by links at longer wavelengths which are much less sensitive to scattering agents in the atmosphere.