An optical waveguide structure has a single port on {TAIL ~ 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 {HEAD ~ a second circular arc optical waveguide portion} connected thereto 
An optical waveguide structure has a single port on { TAIL ~ 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 { HEAD ~ a second circular arc optical waveguide portion } connected thereto
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