Page 19 - Flipped book_fiber optics

TRANSMISSION LOSSES

1.Absorption Loss

 Defined as portion of attenuation resulting from the conversion
of optical power into another energy form such as heat.

 Absorption accounts for 3-5 percent of fiber attenuation.

 Absorption can be limited by controlling the amount of
impurities during the manufacturing process.

 There are two types of absorption loss that is :
 Intrinsic

 Extrinsic

Intrinsic Absorption

 Is caused by the basic fibre-material properties i.e due to
material and electron absorption where:

 Material absorption is a loss mechanism which results in the

dissipation of some of the transmitted optical power into heat
in the optical fibre (around 0.03 dB/km )

 Electron Absorption is intrinsic absorption in the ultraviolet
region caused by electronic absorption. It occurs when a light

particle (photon) interacts with an electron and excites it to a
higher energy level.

 Glass fibres have low absorption than plastic fibres thus

preferred for long haul communications.
 To minimize intrinsic absorption.

 use ultra-pure glass and dopant chemicals to minimize

impurities
 having clean fibre.