| 摘要 |
PROBLEM TO BE SOLVED: To suppress the abnormal loss exclusive of a reflection zone occurring in the discordance of a mode field diameter. SOLUTION: This photosensitive fiber comprises a core 1 and a clad 4 consisting of a clad inner layer 2 deposited around the core 1 and a clad outer layer 3 and is formed with a grating by sensitization at least the core 1. In such a case, the core 1 and the clad inner layer 2 contains a photosensitive dopant for increasing a refractive index and the core 1 contains a nonphotosensitive dopant for increasing the refractive index. The clad inner layer 2 contains a nonphotosensitive dopant for decreasing the refractive index. |
