Engineering Physics

Solved Problems

1.    The refractive indices of core and cladding materials of a step index fibre are 1.48 and 1.45, respectively. Calculate: (i) numerical aperture, (ii) acceptance angle, and (iii) the critical angle at the core-cladding interface and (iv) fractional refractive indices change.

 

(Set-1–May 2006)

Sol: Let the refractive index of core, n₁ = 1.48

and the refractive index of cladding , n₂ = 1.45

1. Numerical aperture (NA)

                   

2. Let θ₀ be the acceptance angle
3. n₂ sin 90 = n₁ sin θ_c [θ_c = critical angle]
4. The fractional refractive ...