Wavelength-selection for high data rate Free Space Optics (FSO) in next generation wireless communications

New results derived from the research in the field or Free Space Optics (FSO) for the qualification of different wavelengths with reference to future communication (including space) are presented. The contribution deals with a thorough discussion of the different optical wavelengths used either for terrestrial as well as for near-Earth and deep space FSO links. Practical results of COST Action IC-0802 are implemented in the modelling of the FSO channel under deteriorating conditions like rain, snow, dust, fog, clouds and other atmospheric effects. It is intended to interconnect well-proved technologies like 850 nm and 1064 nm as well as 1550 nm wavelength with new technologies under development like 10 μm wavelength. Quantum Cascade Lasers (QCLs) are currently experiencing a strong progression. Finally, some recent major performance improvement results obtained by employing some specific modulation and coding schemes are presented.