| 摘要 |
PROBLEM TO BE SOLVED: To realize an optical fiber for high power use with an optical fiber having a porous part extending in the direction of the fiber center axis where lots of air holes are arranged. SOLUTION: The optical fiber 10 is provided with a porous part 12 with lots of the air holes 12a formed which are arranged circularly with a predetermined interval to each other in the cross-section of the fiber. Around the porous part 12, a clad part 14 is arranged, which has a predetermined width in the radial direction of the fiber and has an almost fixed effective refractive index in the radial direction of the fiber which is equivalent to the effective refractive index in the outermost circumferential part of the porous part 12. The porous part 12 forms a light propagation area where a laser beam propagates. The distribution structure of the effective refractive index of the porous part 12 is made to be a chevron distribution (GI type) in which the central part is high in the fiber cross section and the more outward in the radial direction, the lower. the air holes 12a in the porous part 12 have almost the same size, respectively. These air holes 12a are disposed so that the air gap rate becomes larger toward the outer periphery side. COPYRIGHT: (C)2005,JPO&NCIPI |
