The waveguide portion also has a third circular arc optical waveguide portion extending from a first splitting/coupling point side in {HEAD ~ the first circular arc waveguide portion} toward the plural/ports side and having {TAIL ~ a curvature} inverted relative to the first circular arc optical waveguide portion 
The waveguide portion also has a third circular arc optical waveguide portion extending from a first splitting / coupling point side in { HEAD ~ the first circular arc waveguide portion } toward the plural / ports side and having { TAIL ~ a curvature } inverted relative to the first circular arc optical waveguide portion
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH