Patent ID: 7088889

Claim:
An optical splitter having cores and a clad layer that covers the cores, comprising: a main waveguide; a tapered waveguide having a first end portion connected to the main waveguide and side portions that taper and expand from the first end portion toward second end portions; and a split waveguide group including first and second split waveguides connected to the second end portions of the tapered waveguide, wherein the first and second spilt waveguides connected to the second end portions have respective incident ends whose widths differ from each other, a whole width of the split waveguide group is smaller than a width of the tapered waveguide at the second end portions, and step portions are formed between the split waveguide group and the side portions of the tapered waveguide, and wherein an expanding portion is formed at the first end portion of the tapered waveguide, one side of the expanding portion expanding toward one of the side portions of the tapered waveguide more greatly than other side thereof.