Abstract
The aim of this study is to design and study the characteristics of optic fiber made from silica-doped silica.pure silica and 3-doped silica materials (13.5 m / o GeO2 +86.5 m / o SiO2 , 7.0 m / o GeO2 +93.0 m / o SiO2 , 4.1 m / o GeO2 +95.9 m / o SiO2) .Some materials are selected to design an optic fiber .Sellmeir equation are used to calculate the refractive index of the materials .Accordingly 3-types of optical fiber are proposed .
The characteristics of the optical fiber such as :Numerical Aperture ,critical angle ,v-number ,mode number and effective area are calculated. The results show when windows of communication are taken into consideration ,the core of the first fiber optic is made of pure silica ,while the glade is made of 13.5 m/o GeO2+86.5 m/o SiO2 ,this fiber optic is used as fiber of transmission due to the smallness of the numerical aperture in it ,either for the second fiber ,the core was made of pure silica ,while the glade was made of 7.0 m/o GeO2+93.0 m/o SiO2 ,it also can be used as a fibre of transmission or reception according to the application used in it . finally the third fiber has the core made of pure silica ,while the glade was made of 4.1 m/o GeO2+95.9 m/o SiO2 ,it can be used an a fiber of reception due to the width of the numerical aperture in it .