Mumbai University > Electronics and telecommunication > Sem 7 > optical communication and networks

Marks: 05

Years: MAY 2015

In selecting materials for optical fibers, a number of requirements must be satisfied

1. It must be possible to make long, thin, flexible fibers from the material.

2. The material must be transparent at a particular optical wavelength in order for the fiber to guide light efficiently.

3. Physically compatible materials that have slightly different refractive indices for the core and cladding must be available

Materials that satisfy these requirements are glasses and plastics.

$\Rightarrow $ Majority of fibers are made of glass consisting of either silica (SiO_2) or silicate. The variety of available glass fibers with large cores used for short transmission distances to very transparent (low-loss) fibers employed in long haul applications.

Different types of glass fibers are:

$\Rightarrow $ Halide Glass fibers

$\Rightarrow $ Active Glass fibers

$\Rightarrow $ Chalgenide Glass fibers

$\Rightarrow $ Plastic fibers are less widely used because of their substantially higher attenuation than glass fiber. The main use of plastic fibers is in short distance application (several hundred meters) and in abusive environments where the greater mechanical strength of plastic fibers offers an advantage over the use of glass fibers.