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Proceedings Paper

Chirped fiber Bragg grating sensor based on phase delay
Author(s): Qizhen Sun; Deming Liu; Hairong Liu; Li Xia; Ping Shum
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Paper Abstract

A novel design of linearly chirped fiber Bragg grating (LCFBG) based sensor, operating at a single optical wavelength and avoiding the complicated interrogation, is presented and demonstrated. The LCFBG exhibits a good linear relation between the group delay and the wavelength. When a pulsed optical signal goes through the LCFBG with a fixed wavelength within the grating bandwidth, it will be reflected at a particular spatial location along the grating and then will induce a particular time delay, which is direct proportional to the temperature applied on the grating. The time delay is an absolute parameter as well as the wavelength shift, resulting that it is insensitive to optical power fluctuation and loss. In order to measure the time delay accurately, the RF modulation technique is employed. The sensor setup is mainly composed of a narrowband laser source, a Mach-Zehnder electro-optic modulator driven by RF oscillator signal to provide an optical carrier, a 3dB fiber coupler to split the modulated signal into two parts, an optical circulator, a LCFBG with good linear behaviour of group delay spectrum as the sensor head, and two fast photo-detectors. The feasibility of the proposed sensor is demonstrated by numerical simulation, and the simulation result shows that the LCFBG can be used as a good temperature sensor.

Paper Details

Date Published: 21 November 2007
PDF: 8 pages
Proc. SPIE 6781, Passive Components and Fiber-based Devices IV, 67812K (21 November 2007);
Show Author Affiliations
Qizhen Sun, Huazhong Univ. of Science and Technology (China)
Deming Liu, Huazhong Univ. of Science and Technology (China)
Hairong Liu, Huazhong Univ. of Science and Technology (China)
Li Xia, Nanyang Technological Univ. (Singapore)
Ping Shum, Nanyang Technological Univ. (Singapore)

Published in SPIE Proceedings Vol. 6781:
Passive Components and Fiber-based Devices IV
Ming-Jun Li; Jianping Chen; Satoki Kawanishi; Ian H. White, Editor(s)

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