Long Range Free Space Optical Link

Interest on achieving better parameters of the free space optical links is more and more demanded, because of the radio frequencies congestions. There are many advantages to use the free space optical (FSO) link instead of the radio frequency systems. The distance limits of the link can be calculated using the link power budget. The total gain at the optical receiver is an additive value, so we can calculate the power budget of the FSO link as a sum of powers, some of gains and some of looses. Most of these looses are distance dependant. This article deals with the definition of distance and related powers limitations, based on the practical point of view.