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Photonic crystal fiber Mach-Zehnder interferometer for refractive index sensing.

Wang JN, Tang JL - Sensors (Basel) (2012)

Bottom Line: We report on a refractive index sensor using a photonic crystal fiber (PCF) interferometer which was realized by fusion splicing a short section of PCF (Blaze Photonics, LMA-10) between two standard single mode fibers.The fully collapsed air holes of the PCF at the spice regions allow the coupling of PCF core and cladding modes that makes a Mach-Zehnder interferometer.Experimental results using wavelength-shift interrogation for sensing different concentrations of sucrose solution show that a resolution of 1.62 × 10(-4)-8.88 × 10(-4) RIU or 1.02 × 10(-4)-9.04 × 10(-4) RIU (sensing length for 3.50 or 5.00 cm, respectively) was achieved for refractive indices in the range of 1.333 to 1.422, suggesting that the PCF interferometer are attractive for chemical, biological, biochemical sensing with aqueous solutions, as well as for civil engineering and environmental monitoring applications.

View Article: PubMed Central - PubMed

Affiliation: Department of Construction Engineering, National Yunlin University of Science and Technology, Douliou 64002, Taiwan. wangjn@yuntech.edu.tw

ABSTRACT
We report on a refractive index sensor using a photonic crystal fiber (PCF) interferometer which was realized by fusion splicing a short section of PCF (Blaze Photonics, LMA-10) between two standard single mode fibers. The fully collapsed air holes of the PCF at the spice regions allow the coupling of PCF core and cladding modes that makes a Mach-Zehnder interferometer. The transmission spectrum exhibits sinusoidal interference pattern which shifts differently when the cladding/core surface of the PCF is immersed with different RI of the surrounding medium. Experimental results using wavelength-shift interrogation for sensing different concentrations of sucrose solution show that a resolution of 1.62 × 10(-4)-8.88 × 10(-4) RIU or 1.02 × 10(-4)-9.04 × 10(-4) RIU (sensing length for 3.50 or 5.00 cm, respectively) was achieved for refractive indices in the range of 1.333 to 1.422, suggesting that the PCF interferometer are attractive for chemical, biological, biochemical sensing with aqueous solutions, as well as for civil engineering and environmental monitoring applications.

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Plot of transmission spectra of measured data and sine curve fitting using PCF interferometers with (a) L = 1.34 cm and (b) L = 3.50 cm, respectively.
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f6-sensors-12-02983: Plot of transmission spectra of measured data and sine curve fitting using PCF interferometers with (a) L = 1.34 cm and (b) L = 3.50 cm, respectively.

Mentions: The transmission spectra of a PCF interferometer with different sensing lengths are shown in Figure 5(a–e). High uniform interference fringes were observed over the available spectral range, and the average fringe periods became larger with the decreasing sensing length. The average fringe periods as a function of sensing length, obtained using a linear regression analysis, was determined to be Λ = 60.36×L−1.0347 [R2 = 0.99695, see Figure 5(f)], indicative of the effect of the Mach-Zehnder interferometer. The fringe visibility was calculated for the 15 PCF interferometers and they were in the range of 62.16–89.39%. Since we used the same type of PCF (Blaze Photonics, LMA-10) and the propagation constant deviation involved in the interference could be assumed the same; thus, based on the Figure 5(f), the fringe period of the interferometer was almost inversely proportional to the interferometer length (R2 = 0.996995). In addition, we compared the measured fringe period and the one from a sine curve fitting for each interferometer. Figure 6(a,b) shows the transmission spectra of measured data and sinusoidal wave using a PCF interferometer with length = 1.34 cm and 3.50 cm, respectively. The sinusoidal curve is given by y = Ao + A sin (ωx - φ); where y is the transmission loss, x represents the wavelength, and other parameters are the regression coefficients. Figure 7(a) illustrates the plot of calculated fringe period from sine curve fitting versus sensing length. A correlation was found that the calculated fringe period based on sine curve fitting was almost inversely proportional to the sensing length—Λ = 59.15×L−0.99255 (R2 = 0.99663). The absolute difference value between average measured fringe period and the one from sine curve fitting is calculated as follows:(3)D=/ average measured fringe period − calculated fringe period from sine curve fringe /


Photonic crystal fiber Mach-Zehnder interferometer for refractive index sensing.

Wang JN, Tang JL - Sensors (Basel) (2012)

Plot of transmission spectra of measured data and sine curve fitting using PCF interferometers with (a) L = 1.34 cm and (b) L = 3.50 cm, respectively.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376571&req=5

f6-sensors-12-02983: Plot of transmission spectra of measured data and sine curve fitting using PCF interferometers with (a) L = 1.34 cm and (b) L = 3.50 cm, respectively.
Mentions: The transmission spectra of a PCF interferometer with different sensing lengths are shown in Figure 5(a–e). High uniform interference fringes were observed over the available spectral range, and the average fringe periods became larger with the decreasing sensing length. The average fringe periods as a function of sensing length, obtained using a linear regression analysis, was determined to be Λ = 60.36×L−1.0347 [R2 = 0.99695, see Figure 5(f)], indicative of the effect of the Mach-Zehnder interferometer. The fringe visibility was calculated for the 15 PCF interferometers and they were in the range of 62.16–89.39%. Since we used the same type of PCF (Blaze Photonics, LMA-10) and the propagation constant deviation involved in the interference could be assumed the same; thus, based on the Figure 5(f), the fringe period of the interferometer was almost inversely proportional to the interferometer length (R2 = 0.996995). In addition, we compared the measured fringe period and the one from a sine curve fitting for each interferometer. Figure 6(a,b) shows the transmission spectra of measured data and sinusoidal wave using a PCF interferometer with length = 1.34 cm and 3.50 cm, respectively. The sinusoidal curve is given by y = Ao + A sin (ωx - φ); where y is the transmission loss, x represents the wavelength, and other parameters are the regression coefficients. Figure 7(a) illustrates the plot of calculated fringe period from sine curve fitting versus sensing length. A correlation was found that the calculated fringe period based on sine curve fitting was almost inversely proportional to the sensing length—Λ = 59.15×L−0.99255 (R2 = 0.99663). The absolute difference value between average measured fringe period and the one from sine curve fitting is calculated as follows:(3)D=/ average measured fringe period − calculated fringe period from sine curve fringe /

Bottom Line: We report on a refractive index sensor using a photonic crystal fiber (PCF) interferometer which was realized by fusion splicing a short section of PCF (Blaze Photonics, LMA-10) between two standard single mode fibers.The fully collapsed air holes of the PCF at the spice regions allow the coupling of PCF core and cladding modes that makes a Mach-Zehnder interferometer.Experimental results using wavelength-shift interrogation for sensing different concentrations of sucrose solution show that a resolution of 1.62 × 10(-4)-8.88 × 10(-4) RIU or 1.02 × 10(-4)-9.04 × 10(-4) RIU (sensing length for 3.50 or 5.00 cm, respectively) was achieved for refractive indices in the range of 1.333 to 1.422, suggesting that the PCF interferometer are attractive for chemical, biological, biochemical sensing with aqueous solutions, as well as for civil engineering and environmental monitoring applications.

View Article: PubMed Central - PubMed

Affiliation: Department of Construction Engineering, National Yunlin University of Science and Technology, Douliou 64002, Taiwan. wangjn@yuntech.edu.tw

ABSTRACT
We report on a refractive index sensor using a photonic crystal fiber (PCF) interferometer which was realized by fusion splicing a short section of PCF (Blaze Photonics, LMA-10) between two standard single mode fibers. The fully collapsed air holes of the PCF at the spice regions allow the coupling of PCF core and cladding modes that makes a Mach-Zehnder interferometer. The transmission spectrum exhibits sinusoidal interference pattern which shifts differently when the cladding/core surface of the PCF is immersed with different RI of the surrounding medium. Experimental results using wavelength-shift interrogation for sensing different concentrations of sucrose solution show that a resolution of 1.62 × 10(-4)-8.88 × 10(-4) RIU or 1.02 × 10(-4)-9.04 × 10(-4) RIU (sensing length for 3.50 or 5.00 cm, respectively) was achieved for refractive indices in the range of 1.333 to 1.422, suggesting that the PCF interferometer are attractive for chemical, biological, biochemical sensing with aqueous solutions, as well as for civil engineering and environmental monitoring applications.

Show MeSH
Related in: MedlinePlus