Extrinsic and Intrinsic Attenuation
Attenuation is defined as the loss of optical power over a set distance. A fiber with a lower attenuation will allow more power to reach a receiver than a fiber with higher attenuation.
Attenuation may be categorized as intrinsic and extrinsic.
It is loss due to inherent mechanism within the fiber. Intrinsic attenuation may occur as
(i) Absorption - Natural impurities in the glass absorb light energy (ii) Scattering - Light rays traveling in the core reflect from small imperfections into a new pathway that may be lost through the cladding
Extrinsic Attenuation It is loss due to external sources. Extrinsic attenuation may occur due to:
(i) Macro bending - The fiber is sharply bent so that the light traveling down the fiber cannot make the turn & is lost in the cladding. (ii) Micro bending - Macro bending or small bends in the fiber caused by crushing, contraction etc. These bends may not be visible with the naked eye.
Attenuation is measured in decibels (dB). A dB represents the comparison between the transmitted and received power in a system.