Hello Sarath
you are in a way duplicating your query. Fayiqa has already provided you with the required link and the .osd file of the bidirectional fiber which clearly shows the use of optical delay and for that matter as fayiqa has beautifully explained u need to increase the nuber of iterations more than one and keeping it about three or four. i suggest to go through your own post again.
Regards
Burhan