Derive the formula for numerical aperture of step index fibre and give its physical significance. The N.A. of an optical fibre is 0.5 and core refractive index is 1.54.

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written 5.9 years ago by

vermavarsha432 • 1.0k

modified 4.7 years ago by

sanketshingote • 100

Find the refractive index of cladding.

advanced engineering physics

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written 5.8 years ago by

vermavarsha432 • 1.0k

Numerical Aperture is the ability of fiber to collect the light from the source and save the light inside it by maintaining the condition of total internal reflection.

Consider a light ray entering from a medium of refractive index n0 into the fiber with a core of refractive index n1 which is slightly greater than that of the cladding n:

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Thus the formula for numerical aperture of step index fiber has been derived.

PHYSICAL SIGNIFICANCE OF NUMERICAL APERTURE

1. It is the parameter which provides information about the acceptance angle.

2. Smaller N.A. is not an advantage because it makes it harder to launch power into fiber.

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