Novel long-period fiber grating based on hybrid structure for sensing application
| Autor: | Zi-Yu Weng, 翁梓彧 |
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| Rok vydání: | 2011 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 Based on the structure of long-period grating (LPG), the study developed two kinds of hybrid long-period fiber grating (LPFG) sensing devices which can measure environment parameters with very high sensitivity. The first hybrid device is based on a tapered fiber coated silica periodical thin film with thickness of around 1~2m on one side of the tapered region to form an asymmetric LPG on the taper. The tapered fiber is well known very sensitive to the surrounding variation. Once the tapered fiber combined with the proposed LPG and operated under a leakage coupling situation. The coupling light of the LPG based on the Fresnel reflection return to the tapered fiber and generate resonant dips. By measuring wavelength shifts of the spectral response, ultrasensitive measurement can be demonstrated. The second hybrid sensor is based on a reflective long-period fiber grating (RLPFG) incorporated with a fiber endface overlaying an extremely small melting tin (Sn). An air gap can be naturally formed around the fiber endface due to the cohesion effect of the melting tin. The air-gap cavity formed as a low finesse air gap fiber Fabry-Perot interferometer (AG-FFPI) in the hybrid sensor. It can be combined with a RLPFG to form a smart and hybrid fiber sensor for simultaneously measuring multiple parameters. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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