hi tanveer,
i agree with alistu on this, you must avoid two discussion on same topic.
click on the fiber the window will apper with its parameters, in LENGTH select sweep mode, increse the iteration as desired by you.
for example; provide iteration to 50, then in seep mode select linear mode and length will go from 1 t0 50 km.
after the simulation, you can take results on opti2Dgraph.
with regards