Question

A step index optical fiber whose refractive indices of the core and cladding are 1.44 and 1.40 respectively, is surrounded by air. Its numerical aperture is

• A. 0.12
• B. 0.75
• C. 0.06
• D. 0.34

Hint:

NA = \( \sqrt{n_1^2 - n_2^2} \) where \( n_1 \) is core and \( n_2 \) is cladding refractive index.

Answer 1

The Correct Option is D

Numerical aperture (NA) is given by: \[ NA = \sqrt{n_1^2 - n_2^2} = \sqrt{1.44^2 - 1.40^2} = \sqrt{2.0736 - 1.96} = \sqrt{0.1136} \approx 0.34 \]