| 摘要 |
In order to create a diffraction grating in an optical fiber with a predetermined pattern of the refractive index, an ultraviolet radiation beam (3) is scanned (5,8) along a photosensitive portion (F') of the fiber through a phase mask (9) and, during the scan, the beam intensity (4) and the mask-fiber distance (10) are controlled moment by moment in such a way as to obtain the desired patterns of the mean value and of the envelope of the refractive index, respectively. <IMAGE> |
