Merely tagging change sets with task Numbers isn't enough; one has to be able to say "merge feature X into branch y" and have the source control identify every change set that is needed.

Then, detailed design for the structure of Y-branch optical power splitter is followed.

The basic principles and simulation methods of a null-coupler-based OADM are studied firstly, especially in the crosstalk of a Y-branch structure and the coupling properties of a tilted grating.