Question

A step index fiber has a numerical aperture of NA = 0.1. The refractive index of its cladding is 1.465. What is the largest core diameter for which the fiber remains single-moded at the wavelength of 1.3 μm?

Answer 1

Answer:

diameter = 9.951 × $10^{-6}$ m

Explanation:

given data

NA = 0.1

refractive index = 1.465

wavelength = 1.3 μm

to find out

What is the largest core diameter for which the fiber remains single-mode

solution

we know that for single mode v number is

V ≤ 2.405

and v = $\frac{2*\pi *r}{ wavelength} NA$

here r is radius    

so we can say

$\frac{2*\pi *r}{ wavelength} NA$    = 2.405

put here value

$\frac{2*\pi *r}{1.3*10^{-6}} 0.1$    = 2.405

solve it we get r

r = 4.975979 × $x^{-6}$ m

so diameter is = 2  ×  4.975979 × $10^{-6}$ m

diameter = 9.951 × $10^{-6}$ m