| 摘要 |
PURPOSE:To rapidly detect an optical fiber cut-off wavelength, by investigating the magnitude relation between the light output change quantities after and before bending is imparted to an optical fiber, and a predetermined threshold value and judging the magnitude relation between the cut-off wavelength of the optical fiber and the wavelength of a light source. CONSTITUTION:At first, an optical switch 7 couples an optical cord 6A and an optical fiber 3 to be measured, and the light of a light source 5A having a wavelength lambda1 is incident to the fiber 3 in such a state that the fiber 3 is straight and the light output P1 thereof is measured by a light detector 4. Next, light output P2 is measured by the detector 4 in such a state 3A that the fiber 3 is bent by a bending imparting part 8. Next, the switch 7 is changed over to successively couple the fiber 3 with optical cords 6B, 6C. The light outputs P3-P6 are measured with respect to respective couplings in the straight and bent states of the fiber 3. From the light outputs P1-P6 thus calculated, the magnitude relation between the cut-off wavelength of the fiber 3 and the wavelengths lambda1, lambda2, lambda3 of the light source is judged. By this method, the cut-off wavelength of the optical fiber can be rapidly checked. |
