The index of refraction of the cladding of an optical fiber

The index of refraction of the cladding of an optical fiber is 1.47, and the index of refraction ofthe core is 1.52. Using 1.52* sin(theta_C) = 1.47* sin (90 degree), solve for the critical angle in the fiber

Solution

For any two media placed right next to each other, there exists an angle such that any ray travelling from the index of higher refractive index fails to emerge on the other side of the interface between the media. This angle is defined as the critical angle, and for this particular angle the refracted ray makes an angle of 90 degrees with the normal.

As has been mentioned, the snell\'s law gives us the equation:

1.52 x Sinc = 1.47 Sin 90

Hence, Sin c = 0.967

or, c = 75.26 degrees.

Therefore the critical angle for a ray travelling inside the core would be 75.26 degrees.