Scattering loss

Scattering loss

Scattering losses in glass arises from macroscopic variations in the material density From compositional Fluctuations and from structural inhomogeneities or defects occurring during

 fibre manufacture.
    
Glass is made up of several oxides ,such as Sio2,Geo2, and P2O5 compositional fluctuations 

can occur.Glass structure naturally contain regions in which the molecular density is either

higher or lower than the average density in the glass. These two effects give rise to

refractive index variations which occur with in the glass over distances that are small compared with the wavelength.

For a single component glass the scattering loss at a wavelength λ resulting from density fluctuations

can be given as

where n is the refractive index ,K_B is Boltzmann constant , β_{T is the isothermal compressibility of the} 

_{material , and} T_{f  is fictive temperature.}

_{alternately we use other relation}

   

where p is the photo elastic coefficient .

for multicomponent glasses the scattering is given by

                                                  

where is square of mean square refracive index fluctuations  over volume of 

structural inhomogeneities and defects created during fibre fabrication  can also cause

 scattering of light out of the fibre. these defects may be in the form of trapped 

gas bubbles ,unreacted starting materials,and crystallized regions in the glass.

the losses of multimode fibres are generally higher than those of single mode fibres.