| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide: a multi-clad fiber in which no high refractive index portion exists in the core center and which is easy to control the refractive index profile; an optical fiber preform suitable for manufacturing the multi-clad fiber; a method for stably manufacturing the optical fiber preform; an optical fiber laser provided with the multi-clad fiber; and an optical amplifier. <P>SOLUTION: The method for manufacturing the optical fiber preform includes a first process for forming a first glass layer 11 containing Ge along the inner surface of a quartz tube 12, a second process for forming a second glass layer 15 containing no Ge along the inner surface of the first glass layer 11, a third process for forming a silica soot 10 on the inner side of the second glass layer 15, a fourth process for adding a dopant to the silica soot 10 and sintering the soot 10, and a fifth process for collapsing the tube obtained in the fourth process. The optical fiber preform is manufactured by the method. The multi-clad fiber is obtained by spinning the optical fiber preform and covering the outer surface of the resulting fiber with a polymer layer. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
