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. 2012;12(6):7318-25.
doi: 10.3390/s120607318. Epub 2012 May 30.

A hybrid LPG/CFBG for highly sensitive refractive index measurements

An Sun  1 , Zhishen Wu
Affiliations

A hybrid LPG/CFBG for highly sensitive refractive index measurements

An Sun et al. Sensors (Basel). 2012.

Abstract

A simple and high sensitive method employing a hybrid long period grating (LPG)/chirped fiber Bragg grating (CFBG) for refractive index (RI) measurements is proposed and investigated experimentally. The wide wavelength range of backward cladding modes are excited through the coupling and recoupling between LPG and CFBG. Experimental results indicate that the recoupled cladding modes between LPG and CFBG and core mode are modulated by the surrounding RI and highly sensitive RI measurements can be achieved by simply measuring the reflected intensity changes of the recoupled cladding modes and core mode.

Keywords: cladding modes; hybrid FBG/LPG; optical fiber sensor; refractive index.

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Figures

Figure 1.
Figure 1.
Schematic diagram of hybrid LPG/CFBG refractometer.
Figure 2.
Figure 2.
Spectra of LPG and CFBG before and after splicing.
Figure 3.
Figure 3.
Experimental setup of hybrid LPG/CFBG for RI measurement.
Figure 4.
Figure 4.
Reflected spectrum changes of hybrid LPG/CFBG at different RI.
Figure 5.
Figure 5.
Reflected power of hybrid LPG/CFBG versus RI.
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