{TAIL ~ An optical waveguide structure} has a single port on one input/output side, a plurality of {HEAD ~ 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 
{ TAIL ~ An optical waveguide structure } has a single port on one input / output side , a plurality of { HEAD ~ 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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