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.
Sol: Let the refractive index of core, n1 = 1.48
and the refractive index of cladding , n2 = 1.45