Abstract
An in-line fiber Fabry-Perot interferometer (FPI) based on the hollow-core photonic crystal fiber (HCPCF) for refractive index (RI) measurement is proposed in this paper. The FPI is formed by splicing both ends of a short section of the HCPCF to single mode fibers (SMFs) and cleaving the SMF pigtail to a proper length. The RI response of the sensor is analyzed theoretically and demonstrated experimentally. The results show that the FPI sensor has linear response to external RI and good repeatability. The sensitivity calculated from the maximum fringe contrast is –136 dB/RIU. A new spectrum differential integration (SDI) method for signal processing is also presented in this study. In this method, the RI is obtained from the integrated intensity of the absolute difference between the interference spectrum and its smoothed spectrum. The results show that the sensitivity obtained from the integrated intensity is about –1.34×105 dB/RIU. Compared with the maximum fringe contrast method, the new SDI method can provide the higher sensitivity, better linearity, improved reliability, and accuracy, and it’s also convenient for automatic and fast signal processing in real-time monitoring of RI.
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D. J. Feng, G. X. Liu, X. L. Liu, M. S. Jiang, and Q. M. Sui, “Refractive index sensor based on plastic optical fiber with tapered structure,” Applied Optics, 2014, 53(10): 2007–2011.
J. Zhao, S. Q. Cao, C. R. Liao, Y. Wang, G. J. Wang, X. Z. Xu, et al., “Surface plasmon resonance refractive sensor based on silver-coated side-polished fiber,” Sensors and Actuators B: Chemical, 2016, 230: 206–211.
S. Singh, S. K. Mishra, and B. D. Gupta, “Sensitivity enhancement of a surface plasmon resonance based fibre optic refractive index sensor utilizing an additional layer of oxides,” Sensors and Actuators A: Physical, 2013, 193: 136–140.
G. Tsigaridas, D. Polyzos, A. Ioannou, M. Fakis, and P. Persephonis, “Theoretical and experimental study of refractive index sensors based on etched fiber Bragg gratings,” Sensors and Actuators A: Physical, 2014, 209: 9–15.
Y. Ran, L. Jin, L. P. Sun, J. Li, and B. O. Guan, “Temperature-compensated refractive-index sensing using a single Bragg grating in an abrupt fiber taper,” IEEE Photonics Journal, 2013, 5(2): 7100208–7100208.
B. Q. Jiang, X. Lu, X. T. Gan, M. Qi, Y. D. Wang, L. Han, et al., “Graphene-coated tilted fiber-Bragg grating for enhanced sensing in low-refractive-index region,” Optics Letters, 2015, 40(17): 3994–3997.
A. Singh, “Long period fiber grating based refractive index sensor with enhanced sensitivity using Michelson interferometric arrangement,” Photonic Sensors, 2015, 5(2): 172–179.
L. Coelho, D. Viegas, J. L. Santos, and J. M. M. M. de Almeida, “Enhanced refractive index sensing characteristics of optical fibre long period grating coated with titanium dioxide thin films,” Sensors and Actuators B: Chemical, 2014, 202: 929–934.
Y. Li, Z. B. Liu, and S. S. Jian, “Multimode interference refractive index sensor based on coreless fiber,” Photonic Sensors, 2014, 4(1): 21–27.
Y. Li, E. Harris, L. Chen, and X. Y. Bao, “Application of spectrum differential integration method in an in-line fiber Mach-Zehnder refractive index sensor,” Optics Express, 2010, 18(8): 8135–8143.
R. Gao, Y. Jiang, W. H. Ding, Z. Wang, and D. Liu, “Filmed extrinsic Fabry-Perot interferometric sensors for the measurement of arbitrary refractive index of liquid,” Sensors and Actuators B: Chemical, 2013, 177: 924–928.
C. L. Lee, J. M. Hsu, J. S. Horng, W. Y. Sung, and C. M. Li, “Microcavity fiber Fabry-Pérot interferometer with an embedded golden thin film,” IEEE Photonics Technology Letters, 2013, 25(9): 833–836.
Z. L. Ran, Y. J. Rao, W. J. Liu, X. Liao, and K. S. Chiang, “Laser-micromachined Fabry-Perot optical fiber tip sensor for high-resolution temperature-independent measurement of refractive index,” Optics Express, 2008, 16(3): 2252–2263.
Y. Gong, Y. Guo, Y. J. Rao, T. Zhao, and Y. Wu, “Fiber-optic Fabry-Perot sensor based on periodic focusing effect of graded-index multimode fibers,” IEEE Photonics Technology Letters, 2010, 22(23): 1708–1710.
D. Wu, Y. Huang, J. Y. Fu, and G. Y. Wang, “Fiber Fabry-Perot tip sensor based on multimode photonic crystal fiber,” Optics Communications, 2015, 338: 288–291.
D. Wu, W. Huang, G. Y. Wang, J. Y. Fu, and Y. Y. Chen, “In-line fiber Fabry-Perot refractive index tip sensor based on photonic crystal fiber and spectrum differential integration method,” Optics Communications, 2014, 313: 270–275.
B. Qi, G. R. Pickrell, J. C. Xu, P. Zhang, Y. H. Duan, W. Peng, et al., “Novel data processing techniques for dispersive white light interferometer,” Optical Engineering, 2003, 42(11): 3165–3171.
Y. Jiang, “High-resolution interrogation technique for fiber optic extrinsic Fabry-Perot interferometric sensors by the peak-to-peak method,” Applied Optics, 2008, 47(7): 925–932.
C. J. Qi, M. H. Yang, D. W. Lee, W. J. Xie, and J. X. Dai, “Improved sensitivity of fiber Fabry-Perot interferometer based on phase-tracking algorithm,” IEEE Sensors Journal, 2015, 15(10): 5834–5838.
X. H. Liu, M. S. Jiang, Q. M. Sui, and F. R. Song, “Temperature sensitivity characteristics of HCPCF-based Fabry-Perot interferometer,” Optics Communications, 2016, 359: 322–328.
M. S. Jiang, Q. M. Sui, Z. W. Jin, F. Y. Zhang, and L. Jia, “Temperature-independent optical fiber Fabry-Perot refractive-index sensor based on hollow-core photonic crystal fiber,” Optik–International Journal for Light and Electorn Optics, 2014, 125(13): 3295–3298.
A. Savitzky and M. J. E. Golay, “Smoothing and differentiation of data by simplified least squares procedures,” Analytical Chemistry, 1964, 36(8): 1627–1639.
Acknowledgment
This research is supported by the National Natural Science Foundations of China (Grant Nos. 61174018 and 61505097) and Fundamental research funds of Shandong University, China (Grant No. 2014YQ009).
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Liu, X., Jiang, M., Sui, Q. et al. HCPCF-based in-line fiber Fabry-Perot refractometer and high sensitivity signal processing method. Photonic Sens 7, 336–344 (2017). https://doi.org/10.1007/s13320-017-0392-6
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DOI: https://doi.org/10.1007/s13320-017-0392-6