{HEAD ~ An optical waveguide structure} has {TAIL ~ a single port} on one input/output side, a plurality of ports on another input/output side and an S curve optical waveguide portion arranged on the outermost side of the waveguide structure and including a first circular arc optical waveguide portion and a second circular arc optical waveguide portion connected thereto 
has
{ HEAD ~ An optical waveguide structure } has { TAIL ~ a single port } on one input / output side , a plurality of ports on another input / output side and an S curve optical waveguide portion arranged on the outermost side of the waveguide structure and including a first circular arc optical waveguide portion and a second circular arc optical waveguide portion connected thereto
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