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Proceedings Paper

Theoretical analysis of sensing character of long period fiber grating coated with gas-sensitive film
Author(s): Yong Peng; Yizhuo Wang
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Paper Abstract

Firstly we studied the sensitivity of long-period fiber gratings (LPFG) to the refractive index of ambient medium using the coupled modes theory. Then we presented numerical calculation based on long period fiber grating to show the relationship between the resonant wavelength of transmission spectrum and the ambient refractive index. Secondly we analyzed the optical mechanics of the semiconductor oxide film with gas-sensitivity and found that when touching the thin film gas can make its extinction coefficient, absorption coefficient and corresponding refractive index change. Thus we can coat the grating surface with gas-sensitive film and make use of the character that the refractive index will change with the component and density of ambient gas. Furthermore the change will influence the resonant wavelength of transmission spectrum of LPFG therefore we can get information about the gas component and density by way of monitoring changes of wavelength. The LPFG is more sensitive to ambient refractive index than fiber and the sensed signal is wavelength-modulated so the signal is not reflected by the fluctuation of light intensity and the fiber loss. Therefore the LPFG is more sensitive than intensity-type fiber gas sensor.

Paper Details

Date Published: 9 December 2005
PDF: 7 pages
Proc. SPIE 6024, ICO20: Optical Devices and Instruments, 60241K (9 December 2005); doi: 10.1117/12.666865
Show Author Affiliations
Yong Peng, Dalian Maritime Univ. (China)
Yizhuo Wang, Dalian Maritime Univ. (China)

Published in SPIE Proceedings Vol. 6024:
ICO20: Optical Devices and Instruments
James C. Wyant; X. J. Zhang, Editor(s)

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