Experimental study of coherent detection BPSK modulated communication link under controlled fog atmospheric conditions

In this paper, the effect of fog on a free space optical (FSO) communication link employing a coherent detection binary-phase-shift-keying modulation (BPSK) scheme is experimentally investigated. The experimental work is carried out in a controlled laboratory environment where fog could be generated and its impact on the FSO link investigated. The experimental data obtained is compared to the theoretical prevision. The paper also presents how the data transmission performance depends on the exact position of the fog source within the chamber. The beam divergence loss is analyzed and optical solutions are shown. Moreover, the improvement of the beam spot size through applying a combination of concave and convex mirrors which consequently improve the link performance is also studied.