Comparison of 830 nm and 1550 nm based free space optical communications link under controlled fog conditions

In this paper, we compare the fog attenuation of free space optical (FSO) communication systems operating at infrared wavelengths of 830 and 1550 nm in the controlled laboratory based fog environment. The fog is generated and controlled homogeneously along the atmospheric chamber of length 5.5 m. The visibility (V) is measured to characterize the fog within the chamber using Koschmieder relationship at 550 nm. We show that the 1550 nm wavelength has considerably lower optical loss than 830 nm in dense to moderate fog conditions with the average loss difference of 100 dB for dense fog (V<; 70 m), 23 dB for thick fog (V = 250 m) and 8 dB for moderate fog (V= 500 m) for a link range of 1 km.