Engineering Physics

11.5 Differences between step index fibres and graded index fibres

Step Index Fibre	Graded Index Fibre
1. The refractive index of the core is uniform and step or abrupt change in refractive index takes place at the interface of core and cladding in step index fibres.	1. The refractive index of core is non-uniform, the refractive index of core decreases parabolically from the axis of the fibre to its surface.
2. The light rays propagate in zig-zag manner inside the core. The rays travel in the fibre as meridional rays and they cross the fibre axis for every reflection.	2. The light rays propagate in the form of skew rays or helical rays. They will not cross the fibre axis.
3. Signal distortion is more in case of high-angle rays ...