| 摘要 |
PROBLEM TO BE SOLVED: To obtain a measuring method in which an optical waveguide without any face droop is selected by a method wherein a core edge at the optical waveguide is irradiated with a laser beam, an optical fiber is moved in parallel along the core edge and it is measured that the cycle of a change in the intensity of its reflected light is at a specific value or higher. SOLUTION: For example, a laser beam at a wavelength of 1.31μm from a laser light source 2 is incident on an optical fiber 32 via a wavelength-independent bidirectional optical coupler (WIC) 4, a core edge 8 at an optical waveguide 1 is irradiated from the tip of the optical fiber 32 whose tip is brought close to 0.1 to 10μm from the core edge 8, its reflected light is coupled to the optical fiber 32, it is incident on an optical power meter 5 via the WIC 4, and the intensity of the reflected light is measured. Then, while the optical fiber 32 is moved in parallel along the core edge by every very small distance from the surface 9 of the optical waveguide 1, the intensity of the reflected light is measured, and the relationship between a distance and the intensity of the reflected light is found. Then, it is confirmed that the cycle width of the intensity of the reflected light is at 30μm or higher and that the face droop of the core edge does not exist. When the optical waveguide is evaluated by this method, the optical waveguide without any face droop can be selected with good efficiency and easily.
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