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

diameter = 9.951 ×
`10^(-6)` m

Step-by-step 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 =
`(2*\pi *r)/( wavelength) NA`

here r is radius

so we can say

`(2*\pi *r)/( wavelength) NA` = 2.405

put here value

`(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