Wednesday, April 22, 2020

Intrinsic and Extrinsic absorption losses in optical fiber

Intrinsic and Extrinsic absorption losses in optical fiber 

Absorption loss is related to the material composition and fabrication process of fiber. Absorption loss results in dissipation of same optical power as hear in the fiber cable. Although glass fiber are extremely pure, some impurities still remain as residues after purification. The amount of absorption by these impurities depends on their concentration and light wavelength. 

  • Intrinsic absorption 

intrinsic absorption in the ultraviolet region is caused by electronic absorption bands, Basically, absorption occurs when a light particle (photon) interacts with an electron and excites it to a higher energy level. The main cause of intrinsic absorption in the infrared region is the characteristic vibration frequency of atomic bonds .in silica glass, absorption is caused by the electromagnetic fild of the optical signal causes intrinsic absorption. light energy is transferred from the electromagnetic field to the bond.

  • Extrinsic absorption 

Extrinsic absorption is much more significant than intrinsic caused by impurities introduced into the fiber material during manufacture- Iron , nickel ,and chromium caused by transition of metal ions to higher energy level Modern fabrication techniques can reduces impurity levels below i part in 1010. For some of the more common metallic impurities in silica fiber the table show the peak attenuation wavelength and the peak attenuation wavelength and the attenuation caused by an allignment tube splice.     


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