| 摘要 |
The optical fiber of the present invention has an input double-clad fiber containing high-reflection FBG, an oscillation double-clad fiber, and an output double-clad fiber containing low-reflection FBG. The output double-clad fiber is formed of a core, a first clad, and a second clad. In the output double-clad fiber, a high refractive-index resin coat section recoated with high refractive-index resin whose refractive index is the same as that of the second clad or greater is disposed at a part where the second clad is partly removed between an output end and the low-reflection FBG. The refractive index of the high refractive-index resin coat section gradually increases along the direction in which light travels through the first clad. |
