| 摘要 |
PURPOSE: To provide a fiber optic coupler with improved coupling characteristics which is especially valid to an optical fiber amplifier. CONSTITUTION: Coupler fibers 31 forms a mutually fused spliced area depending on the wavelength along one part of the length, and the most of light powers with wavelengthλs are spliced among those fibers, and the most of light powers with wavelengthλp introduced to the first fiber 31 are left in it. The mode field diameter of the first coupler fiber 31 is substantially matched with that of a gain fiber 10', and made smaller than that of a second coupler fiber 14'. One end part of the first coupler fiber 31 is spliced to a gain fiber 10. The difference of the mode field diameters among the coupler fibers is sufficient for generating the difference of a coupler fiber propagation constant in the spliced area for deteriorating the coupling ofλs signals. |
