Sathyabhama N R
Volume 6, Issue 1 2022
Page: 38-43
Fog attenuation may be substantial at frequencies of 100 GHz and above. Typically, the liquid water density of fog is 0.05 g/m3 for medium fog (with visibility of around 300 m) and 0.5 g/m3 for thick fog (with visibility of approximately 50 m). The main drawback of employing free space optics (FSO) devices for communication is the interference that the atmosphere causes with light transmission, which affects channel capacity, availability, and connection reliability. Currently, there is debate among FSO equipment manufacturers and users over the best wavelength to employ. Since infrared wavelengths have far less absorption (attenuation) in regular telecommunication glass optical fibres, infrared light is employed in fibre optics to transfer data. This allows the longest distance transmission of data from point to point with minimal loss of power. According to multiple writers, equipment operating at 1550 nm exhibits greater connection availability due to less air attenuation when fog is present. Some argue that all wavelengths are equally muted in dense fogs (visibility < 5 0 0 m) (wavelength independence). A review of fog attenuation in the visible and infrared spectrum is conducted from both an empirical and theoretical perspective. FASCOD computation is used to study laser system performance in the 0.4- to 15-μm spectral zone when there is fog (advection and convection). Both absorption and scattering contribute to the optical fiber's attenuation. The light that is absorbed by the glass molecules and converted to heat is what causes the absorption. A transmission gain of 42% for a lasercom system working at 780 nm is observed compared to the same system working at 1550 nm.
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