Effects of atmospheric turbulence scintillation on the error performance of partially coherent laser communication

In atmospheric laser communication, a laser beam propagating through troposphere atmosphere suffers from irradiance scintillation caused by small but random atmospheric temperature fluctuations. However, the bit error rate (BER) due to such scintillation can be reduced by using a spatially partially coherent laser beam. On the basis of an earlier model of scintillation index for a partially coherent beam propagating in weak turbulence, analytic expressions for the large-scale and small-scale log-intensity variances which are valid under all fluctuation conditions are discussed. The Gamma-Gamma probability density function (PDF) of the received irradiance is used for partially coherent Gaussian beam traversing the atmosphere. Based on the PDF, the BER of atmospheric optical communications using partially coherent laser beam source is analyzed in the case of on-off keying (OOK) modulation. The results show that the use of partially coherent source should be considered as one of the method to improve BER performance induced by turbulence from weak to strong fluctuation.