| 摘要 |
<p>This optical fiber is provided with an input-side double-clad fiber that includes a high-reflection FBG, a double-clad fiber for oscillation, and an output-side double-clad fiber that includes a low-reflection FBG. The output-side double-clad fiber comprises a core, a first clad, and a second clad. A high-refractive-index-resin-coated section, which is recoated with a high-refractive-index resin having a refractive index equivalent to or higher than the refractive index of the second clad, is provided in a section between the low-reflection FBG and the emitting end of the output-side double-clad fiber where a portion of the second clad is removed. The refractive index of the high-refractive-index-resin-coated section gradually increases along the propagation direction of light propagating through the first clad.</p> |
