Bandwidth-tunable optical filters based on the temperature and strain in fiber Bragg gratings.

• Main Authors: Chun-Ying Lin, 林峻瑩
• Other Authors: Wen-Fung Liu
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/12735774730263197883

碩士 === 逢甲大學 === 光電物理研究所 === 92 === In the fields of fiber optics, the fiber grating has become a critical component for applying in fiber-optic sensors or communication systems. Several configurations of sensing the temperature, strain or pressure using fiber gratings have been demonstrated to have a good performance. The content of this thesis is to investigate the bandwidth-tunable fiber sensor based on the temperature gradient or strain gradient in a uniform tapered fiber grating. We have demonstrated that the bandwidth of a uniform grating can be tuned as a chirped-tunable grating. The temperature gradient along the axis of the grating has been shown in experiment, which causes the 3-dB bandwidth of the grating to become wider and the grating reflectivity to decrease due to the grating period from a uniform distribution to a chirped period. When the tapered fiber grating is stressed in the axis direction to create a strain gradient, the grating bandwidth is tuned, the center wavelength is increased linearly, and the reflectivity is decreased. This bandwidth-tunable fiber grating can practically apply not only in fiber sensors but also in the CWDM system. The grating bandwidth can be tuned at the maximum of 20nm for the applications of an CWDM system to add/drop the required optical signals.