| 摘要 |
PROBLEM TO BE SOLVED: To make the occupying space small and to reduce the size, by forming a groove crossing the optical waveguide of an optical waveguide substrate and changing the wavelength to be taken out by inserting, fixing, etc., of an optical filter element changed in thickness into the groove. SOLUTION: The groove 25 crossing the branch waveguide parts 241 to 244 is formed on the optical wavehguide forming surface of the optical waveguide substrate 21. The optical filter element 26 is inserted and fixed into the groove 25. The optical filter element 26 is formed into a thin film shape obtd. by alternately laminating films of a high refractive index and a low refractive index. The film thickness thereof is gradually changed along the groove 25. Namely, the thickness W2 at the other end of the optical filter element 26 less larger than the thickness W1 at one end and the film thickness gradually changed therebetween (A). Another method is to make the respective adjacent intervals of the branch waveguide parts 241 to 244 gradually larger the further from the main waveguide 23 in order to change the wavelength of the light to be taken out by making the film thickness of the optical filter element 26 constant and changing the angle of the incident light on the optical filter element 26. |
