| 摘要 |
<p>A method of avoiding phase discontinuities between adjacent sections of a long Bragg grating written section-by-section in an optical fibre (11) uses masks (10a, 10b, ..., 10f) with alignment parts additional to their writing parts. Each alignment part is a replica of a portion of the writing part of the adjacent mask. The writing of the Bragg grating produces an associated absorption grating and so, for light directed in series through the alignment part of the mask and the already-written previous section of the grating, transmission is at a maximum when the mask is moved into exact registry. Fine adjustment of mask position is made to find this condition before writing with this mask is commenced. <IMAGE></p> |
