Comparison of atmospheric losses in 850 nm and 1550 nm optical windows

Atmospheric phenomena such as scattering and turbulence can cause large variation in laser beam attenuation of free space optics systems. The paper deals with comparison of the atmospheric attenuation caused by both these phenomena and with comparison of the link availability affected by scattering at 850 nm and 1550 nm. The dispersive behavior of the atmosphere is modeled using the Mie scattering and the power loss caused by turbulence is calculated under assumption that the probability of having a too-high short-term bit error rate is kept under a certain value. The availability calculation is based on statistical evaluation of visibility data collected at several airports in Europe and takes into consideration the link distance and power link margin.