Patent ID: 7949212

Claim:
An optical waveguide element, comprising first and second optical waveguides formed to have different waveguide modes of guided lights, whose polarized waves are different, wherein the first optical waveguide includes a directional coupling region, and the second optical waveguide includes an incident side waveguide, which has the directional coupling region and which is provided in parallel with the first optical waveguide, and the second optical waveguide includes an exit side waveguide, which is extended from the incident side waveguide and which is bent in the direction that recedes from the first optical waveguide, the second optical waveguide is formed in a taper shape such that a width of the incident side waveguide gradually increases from an incident side to an exit side, reflection suppression means for restricting a reflected light heading from an exit side to an incident side is provided on the incident side of the incident side waveguide of the second optical waveguide, the reflection suppression means is formed in a taper shape such that a width of the second optical waveguide gradually increases from the incident side of the second optical waveguide to the exit side, and the reflection suppression means is formed in a taper shape such that the incident side of the second optical waveguide forms an acute angle shape, and is positioned in the directional coupling region, a gap between the first optical waveguide and the second optical waveguide is not changed in the portion where the reflection suppression means is positioned, and a gap between the exit side waveguide of the second optical waveguide and the first optical waveguide gradually increases from the incident side of the second optical waveguide to the exit side.