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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 the relationship between sensitivity and sensing length for PCF interferometer at (a) first refractive index area (RI = 1.333 – 1.370); (b) second refractive index area (RI = 1.373 – 1.403); and (c) third refractive index area (RI = 1.403 – 1.422).
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f13-sensors-12-02983: Plot of the relationship between sensitivity and sensing length for PCF interferometer at (a) first refractive index area (RI = 1.333 – 1.370); (b) second refractive index area (RI = 1.373 – 1.403); and (c) third refractive index area (RI = 1.403 – 1.422).

Mentions: A red shift in the resonance wavelength was observed with the increase of RI as shown in Figures 8 to 12. The graphs display transmission spectra versus air and RI for different concentrations of sucrose solution using a PCF interferometer. For example, Figure 12(b) shows a linear fit (R2 = 0.9971, 0.9891, and 0.9792) to the plot of the wavelength shift vs. RI of the sucrose solution. For the RI sensitivity of a 5.00-cm PCF interferometer was determined by the slopes of three-stage linear fits and it had 309 nm/RIU, 251 nm/RIU, and 326 nm/RIU in the RI range of 1.333–1.373, 1.373–1.403, and 1.403–1.422, respectively. We have collected and analyzed the data considering different sensing lengths in the PCF interferometer. Figure 13(a–c) shows the box plots of interferometer resolution (sensor resolution = 3σ/m, σ = standard deviation of sensor response in measuring the blank sample, m = slope) versus the sensing length (1.34–5.0 cm) for three-stage RI areas. Studies presented here demonstrate that these PCF interferometers (sensing length = 1.34, 2.67, 3.50, 4.40, or 5.00 cm) could provide a sensor resolution of 3.28 × 10−3–5.20 × 10−5 RIU for refractive indices in the range of 1.333 to 1.422. For example, the resolution of PCF interferometer was as low as in the range of 1.62 × 10−4–8.88 × 10−4 RIU or 1.02 × 10−4–9.04 × 10−4 RIU when sensing length is equal to 3.50 cm or 5.00 cm, respectively. Based on Figure 13(a–c), the five different lengths of PCF interferometers were evaluated and the effect of sensor length was discussed about the sensor sensitivity (nm/RIU) and sensitivity variation (sensitivity range). The PCF interferometers with sensing length 3.50 cm and 5.00 cm had both better sensor sensitivity and smaller sensitivity variation than those of other PCF interferometers. Thus, the 3.00-cm and 5.00-cm PCF interferometers possessed comparable performance for the resolution in the range of 1.62 × 10−4–8.88 × 10−4 RIU and 1.02 × 10−4–9.04 × 10−4 RIU, respectively. In addition, the 3.00-cm and 5.00-cm PCF interferometers exhibited relatively small sensitivity variation (less than 5.71 nm/RIU and 5.05 nm/RIU, respectively). However, if the 5.00-cm PCF interferometer is used, the bending effect and package technique should be noticed.


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

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

Plot of the relationship between sensitivity and sensing length for PCF interferometer at (a) first refractive index area (RI = 1.333 – 1.370); (b) second refractive index area (RI = 1.373 – 1.403); and (c) third refractive index area (RI = 1.403 – 1.422).
© Copyright Policy
Related In: Results  -  Collection

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

f13-sensors-12-02983: Plot of the relationship between sensitivity and sensing length for PCF interferometer at (a) first refractive index area (RI = 1.333 – 1.370); (b) second refractive index area (RI = 1.373 – 1.403); and (c) third refractive index area (RI = 1.403 – 1.422).
Mentions: A red shift in the resonance wavelength was observed with the increase of RI as shown in Figures 8 to 12. The graphs display transmission spectra versus air and RI for different concentrations of sucrose solution using a PCF interferometer. For example, Figure 12(b) shows a linear fit (R2 = 0.9971, 0.9891, and 0.9792) to the plot of the wavelength shift vs. RI of the sucrose solution. For the RI sensitivity of a 5.00-cm PCF interferometer was determined by the slopes of three-stage linear fits and it had 309 nm/RIU, 251 nm/RIU, and 326 nm/RIU in the RI range of 1.333–1.373, 1.373–1.403, and 1.403–1.422, respectively. We have collected and analyzed the data considering different sensing lengths in the PCF interferometer. Figure 13(a–c) shows the box plots of interferometer resolution (sensor resolution = 3σ/m, σ = standard deviation of sensor response in measuring the blank sample, m = slope) versus the sensing length (1.34–5.0 cm) for three-stage RI areas. Studies presented here demonstrate that these PCF interferometers (sensing length = 1.34, 2.67, 3.50, 4.40, or 5.00 cm) could provide a sensor resolution of 3.28 × 10−3–5.20 × 10−5 RIU for refractive indices in the range of 1.333 to 1.422. For example, the resolution of PCF interferometer was as low as in the range of 1.62 × 10−4–8.88 × 10−4 RIU or 1.02 × 10−4–9.04 × 10−4 RIU when sensing length is equal to 3.50 cm or 5.00 cm, respectively. Based on Figure 13(a–c), the five different lengths of PCF interferometers were evaluated and the effect of sensor length was discussed about the sensor sensitivity (nm/RIU) and sensitivity variation (sensitivity range). The PCF interferometers with sensing length 3.50 cm and 5.00 cm had both better sensor sensitivity and smaller sensitivity variation than those of other PCF interferometers. Thus, the 3.00-cm and 5.00-cm PCF interferometers possessed comparable performance for the resolution in the range of 1.62 × 10−4–8.88 × 10−4 RIU and 1.02 × 10−4–9.04 × 10−4 RIU, respectively. In addition, the 3.00-cm and 5.00-cm PCF interferometers exhibited relatively small sensitivity variation (less than 5.71 nm/RIU and 5.05 nm/RIU, respectively). However, if the 5.00-cm PCF interferometer is used, the bending effect and package technique should be noticed.

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