A $6 \mathrm{~km}$ optical link consists of multimode step-index fiber with a core refractive index of 1.5 and a relative refractive index difference of $1 \%$. Estimate the delay difference between the slowest and fastest modes at the fiber output.

Solution:

We know that in the case of step index fiber, the fiber output. $n_2$ is less than the core refractive index $n_1$.

$ n_1=1.5 \text { and } n_1-n_2=1 \% \text { of } n_1=\frac{1}{100} \times 1.5=.015\\ $

$ n_2=1.5-0.015=1.485\\ $

Now the pulse dispersion for step-index fiber is, …