| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a superstructure fiber Bragg grating without restricting by a phase mask length. SOLUTION: First, a mask and an optical fiber are fixed in their relative positions and are scanned with a beam (step 1). Next, the relative positions of the mask and the optical fiber are moved relative to the longitudinal direction of the optical fiber (step 2). The mask and the optical fiber are fixed in their relative positions and are scanned with the beam in the same manner as in the step 1. Next, the mask is removed and a uniform UV beam is cast to the optical fiber in order to correct and match the deviation of the phase, by which the refractive index can be uniformly changed and the optical length of this segment is changed, by which a phase shift is imparted to the optical fiber (step 3). The position where the fiber is given the phase shift may be other suitable place between both fixed positions. The phase shift quantity is determined by the irradiation time of the UV beam (or the number of light pulses) and whether the necessary phase shift quantity can be achieved or not is determined while reflection spectra are observed. The SSFBG of a free length can be formed by repeating the steps described above. |
