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Optical Engineering

Core-offset-based fiber Bragg grating sensor for refractive index and temperature measurement
Author(s): Xinpu Zhang; Wei Peng; Yun Liu; Qingxu Yu
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Paper Abstract

We present a fiber-optic sensor based on a fiber Bragg grating (FBG) whose core has an offset to that of the lead-in fiber from splicing for simultaneous refractive index (RI) and temperature measurement. Due to the core offset, the core mode in the lead-in fiber is coupled to both the core mode and the cladding modes of the sensing fiber with the FBG. Then the two oppositely propagating code modes, the cladding modes, and the core modes are coupled by the FBG at particular wavelengths determined by the effective indices of the modes and the FBG structure, resulting in two peaks in the FBG reflection spectrum. The peak wavelength corresponding to the core-cladding mode coupling is sensitive to both RI and temperature, while the peak wavelength corresponding to the core-core mode coupling is only sensitive to temperature. Utilizing the difference of two reflection peaks of these coupling modes, both RI and temperature can be detected simultaneously. We fabricate and characterize a sensor. The preliminary experimental results show that it can detect the refractive index in a range of 1.33 to 1.4421, with a temperature sensitivity of 10  pm/°C .

Paper Details

Date Published: 4 February 2013
Opt. Eng. 52(2) 024402 doi: 10.1117/1.OE.52.2.024402
Published in: Optical Engineering Volume 52, Issue 2
Show Author Affiliations
Xinpu Zhang, Dalian Univ. of Technology (China)
Wei Peng, Dalian Univ. of Technology (China)
Yun Liu, Dalian Univ. of Technology (China)
Qingxu Yu, Dalian Univ. of Technology (China)

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