| 摘要 |
PROBLEM TO BE SOLVED: To provide a distributed shift optical fiber capable of enlarging the valid core cross-sectional area, reducing the bend loss and reducing the cut-off wave length. SOLUTION: This distributed shift optical fiber is provided with a center core part 1, the ring part 3 of a refraction index lower than the center core part 1 and a refraction index higher than an intermediate part 2 arranged around the center core part 1 holding the intermediate part 2 of the refraction index lower than the center core part 1 there between and the clad 6 of the refraction index lower than the ring part 3 provided around the ring part 3. In this case, the ring part 3 is composed of a first ring part 3a and the second ring part 3b of the refraction index lower than the first ring part 3a provided in contact with the outer periphery of the first ring part 3a. |
