Hi Feras,
I think there is no such option to plot a 2D graph as you mentioned in optisystem, i did it manually, for the first issue you have mentioned here suppose you want to plot fiber length along X-Axis and Log(BER) along Y-Axis then you take some discrete value of fiber and find the Log(BER) by running simulation and in this way make a table then make a table in Microsoft Excel and there you will find a option for plotting graph and directly the graph will be plotted. This is what I did in my previous research paper. There may be some other easy way. Thanking you.
Regards,
Dhiman