| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a double-clad fiber which cannot produce deterioration or damage on an excitation light source easily when it is used as a fiber for excitation, and to provide an optical fiber amplifier and a fiber laser using the double-clad fiber. <P>SOLUTION: The double-clad fiber 23 includes a core 24, a first clad portion 25 with a refractive index lower than the core provided in the ambients of this core, and a second clad portion 26 with refractive index lower than the first clad portion provided in the ambients of this first clad portion. Further, the fiber has a dopant to which loss in the optical signal of the wavelengthλ<SB>1</SB>becomes larger than the loss in the wavelengthλ<SB>2</SB>of the excitation light source. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
