| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical coupler capable of simultaneously achieving both of high process stability and low polarization dependency, and having low wavelength dependency.SOLUTION: An optical coupler 100 includes a substrate 104, and a clad layer 105 formed on the substrate, and having two waveguides 101a and 101b therein. Three directional couplers 102, 102b, and 102c are formed by bringing a part of the two waveguides close to each other in parallel, and two delay paths 103a and 103b are formed so as to add optical path difference to the two waveguides. The delay path 103a is provided between the directional coupler 102a and the directional coupler 102b, and the delay coupler 103b is provided between the directional coupler 102b and the directional coupler 102c. The three directional couplers have the same uniting characteristics, and the two delay paths have optical path difference different from each other. |
