Page 21 - Flipped book_fiber optics

Extrinsic Absorption

Is caused by unwanted particles or impurities such as iron,
nickel, chromium optical fibres, that are present during the

manufacturing process of fibre optic cables.
 Its also call fibre contamination.

 Also occurs when hydroxyl ions (OH) (due to presence of water

vapor) are introduced into the fibre.
 The light signal is absorbed by natural impurities in the glass.

 To minimize extrinsic absorption:

 use glass refining techniques such as vapor-phase oxidation
during the process of fibre manufacturing which largely

eliminates the effects of these metallic impurities