Experimental study of liquid refractive index sensing based on a U-shaped optical fiber

A U-shaped optical fiber sensing system designed to measure the refractive index of liquid had been proposed. The sensing mechanism of U-shaped optical fiber was discussed. A general single-mode fiber was bent into U-shaped and partially cladding of U-shaped fiber was corroded by HF acid buffer solution. Powers of different diameters of U-shaped fibers had been measured by many experiments. The results showed that the diameter of U-shaped fiber cladding 40 μm and the diameter of U-shaped was 1 cm were suitable to measure liquid refractive index. Then, this U-shaped optical fiber was immersed in liquid, such as pure water, ethanol, acetone and isopropanol, respectively. The evanescent field of the U-shaped fiber should be modulated by the liquid. The optical signal in the U-shaped fiber was measured with the optical spectrum analyzers(OSA). Finally, the experimental results were analyzed, and the spectra in the air was selected as a reference. The relative intensity was obtained for the different liquid. These results showed that the relative intensity of the liquid had a good linear relationship. This sensing device could accurately demarcate refractive index of liquid. It is simple, low cost, and it can also be applied in measuring the level of liquid.

[1]  R. Kopelman,et al.  Submicrometer intracellular chemical optical fiber sensors. , 1992, Science.

[2]  Young-Geun Han,et al.  Measurement of temperature and refractive index based on surface long-period gratings deposited onto a D-shaped photonic crystal fiber , 2011 .

[3]  Fiber optic pressure sensor based on a single-mode fiber F–P cavity , 2010 .

[4]  Yu-Lung Lo,et al.  Ultrahigh sensitivity polarimetric strain sensor based upon D-shaped optical fiber and surface plasmon resonance technology. , 2011, Optics letters.

[5]  A. Vengsarkar,et al.  Optical fiber long-period grating sensors. , 1996, Optics letters.

[6]  Jingjing Guo,et al.  A double-fiber F-P displacement sensor based on direct phase demodulation , 2012, Other Conferences.

[7]  A. Kersey,et al.  Multiplexed fiber Bragg grating strain-sensor system with a fiber Fabry - Perot wavelength filter. , 1993, Optics letters.

[8]  Chien-Hsing Chen,et al.  A Multi-D-Shaped Optical Fiber for Refractive Index Sensing , 2010, Sensors.

[9]  D. Sengupta,et al.  Sensing of hydrostatic pressure using FBG sensor for liquid level measurement , 2012 .

[10]  Chang-Seok Kim,et al.  Long distance fiber Bragg grating strain sensor interrogation using a high speed Raman-based Fourier domain mode-locked fiber laser with recycled residual Raman pump. , 2013, Optics express.

[11]  Bai-Ou Guan,et al.  Temperature-Compensated Refractive-Index Sensing Using a Single Bragg Grating in an Abrupt Fiber Taper , 2013, IEEE Photonics Journal.

[12]  P Meyrueis,et al.  Fiber optic Surface Plasmon Resonance sensor based on wavelength modulation for hydrogen sensing. , 2011, Optics express.

[13]  N. Chen,et al.  Tapered fiber Mach-Zehnder interferometers for vibration and elasticity sensing applications. , 2013, Optics express.

[14]  Takashi Takeo,et al.  U-shaped fiber-optic refractive-index sensor and its applications , 1991, Optics & Photonics.

[15]  Shinn-Fwu Wang.  U-shaped optical fiber sensor based on multiple total internal reflections in heterodyne interferometry , 2009 .

[16]  Deming Liu,et al.  All-solid D-shaped photonic fiber sensor based on surface plasmon resonance , 2012 .

[17]  J. Jensen,et al.  Photonic crystal fiber based evanescent-wave sensor for detection of biomolecules in aqueous solutions , 2003, Conference on Lasers and Electro-Optics, 2003. CLEO '03..

[18]  Chunliu Zhao,et al.  Simultaneous measurement of refractive index and temperature based on a partial cone-shaped FBG , 2012, Other Conferences.

[19]  Jong-Ahn Kim,et al.  Measurement of thickness profile and refractive index variation of a silicon wafer using the optical comb of a femtosecond pulse laser , 2013 .

[20]  Wei Wang,et al.  Michelson interferometer-based fiber-optic sensing of liquid refractive index , 2011 .

[21]  Sang-Jin Choi,et al.  Novel RF Interrogation of a Fiber Bragg Grating Sensor Using Bidirectional Modulation of a Mach-Zehnder Electro-Optical Modulator , 2013, Sensors.