Experimental Investigation of Environment Effects on the FSO Link with Turbulence

The free space optical (FSO) communications link performance is affected by the atmospheric turbulent. In this letter, we experimentally investigate environment effects on the FSO link under different turbulence conditions. We show that the measured refractive index structure parameter C_n², which demonstrates the scintillation strength, varies proportionally with the ambient temperature and the sun elevation angle. We experimentally investigate changes in C_n² with respect to the sun elevation angle and other key parameters that affect the link performance under turbulence and show that higher elevation angle lead to stronger intensity fluctuations at the receiver for a given constant temperature. Moreover, we show that C_n² behaves proportionally as an exponential function of the elevation angle.