However, in Patent Publication 4, only directions of the three splitting waveguides of the Y type waveguide element for connecting them to each other are described and there is no concrete description regarding {HEAD ~ a method} of designing {TAIL ~ a Y type waveguide element} so that optical outputs to the N output waveguides or ports are equally distributed 
of designing
However , in Patent Publication 4 , only directions of the three splitting waveguides of the Y type waveguide element for connecting them to each other are described and there is no concrete description regarding { HEAD ~ a method } of designing { TAIL ~ a Y type waveguide element } so that optical outputs to the N output waveguides or ports are equally distributed
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