Step Index and Graded Index Optical Fibers

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	Step Index Fiber	Graded Index Fiber
1	Refractive index of the core is uniform and undergoes an abrupt change at the interface of core and cladding.	Refractive index of the core varies gradually with radial resistance
2	The diameter of core is about 10 µm in single mode fiber, 50 to 200 µm in multi mode fiber	The diameter of the core is about 50 µm
3	The shape of the propagation of the optical signal is in zig zag manner	The shape of the propagation optical signal appear in the helical or spiral manner.
4	Attenuation losses are of the order 100 dB/km	Attenuation losses are of the order 10dB/km
5	Numerical aperture is more for multi mode step index fibers but it is less in single mode step index fibers	Numerical aperture is less in graded index fibers
6	Single and multimode propagations exist	It is a multi mode fiber