| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for avoiding undesired phase discontinuity between adjacent sections of a long Bragg grating written in an optical fiber for every section and the Bragg reflection grating formed by the method. SOLUTION: A mask having a write part and an adjusting part are sued. Each adjusting part is the replica of a part of the write parts of the adjacent mask. Light having the same wavelength as the wavelength used for writing of a section excites stronger luminescence than that of the area in which the rise of refractive index occurs in the area of a waveguide in which the increase of the refractive index induced by irradiation is not occurred. Consequently, in the light directed to the previous part in which the grating is written through the adjusting part of the mask, the intensity of the luminescent light propagating to the end of the waveguide is changed depending upon the overlapping degree of the bright fringe generated by mask and the irradiated part corresponding to the written Bragg grating. The fine adjustment is performed for acquiring the intensity corresponding to the superposition on a desired level before the start of writing by the mask. |
