hi fady…
i think your problem is related to bidirectionality for which you have to use some delay elements for the working of bidirectional fibers on optiwave in your design which are only for simulation purposes and have no practical significance.
you should refer lesson 5 as the bidirectional topic is discussed in it thoroughly. i hope you will clear your doubts from his lesson.
Also attaching a link for bidirectional-optical-fiber in whcih delay aspect is discussed…..
with regards