4 February 2013 Core-offset-based fiber Bragg grating sensor for refractive index and temperature measurement
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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  pmC .
© 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)
Xinpu Zhang, Xinpu Zhang, Wei Peng, Wei Peng, Yun Liu, Yun Liu, Qingxu Yu, Qingxu Yu, } "Core-offset-based fiber Bragg grating sensor for refractive index and temperature measurement," Optical Engineering 52(2), 024402 (4 February 2013). https://doi.org/10.1117/1.OE.52.2.024402 . Submission:

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