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Fabrication quality analysis of a fiber optic refractive index sensor created by CO2 laser machining.

Chen CH, Yeh BK, Tang JL, Wu WT - Sensors (Basel) (2013)

Bottom Line: Finally, we used the optical fiber sensor fabricated using the improved parameters to measure the refractive indices of various solutions.The results show that a refractive-index resolution of 1.8 × 10(-4) RIU (linear fitting R2 = 0.954) was achieved for sucrose solutions with refractive indices ranging between 1.333 and 1.383.The results provided additional information, specifically, a superior sensor resolution of 5.73 × 10(-5) RIU, and greater linearity at R2 = 0.999.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, National Chung Cheng University, Chiayi 621, Taiwan. saesozj@yahoo.com.tw

ABSTRACT
This study investigates the CO2 laser-stripped partial cladding of silica-based optic fibers with a core diameter of 400 μm, which enables them to sense the refractive index of the surrounding environment. However, inappropriate treatments during the machining process can generate a number of defects in the optic fiber sensors. Therefore, the quality of optic fiber sensors fabricated using CO2 laser machining must be analyzed. The results show that analysis of the fiber core size after machining can provide preliminary defect detection, and qualitative analysis of the optical transmission defects can be used to identify imperfections that are difficult to observe through size analysis. To more precisely and quantitatively detect fabrication defects, we included a tensile test and numerical aperture measurements in this study. After a series of quality inspections, we proposed improvements to the existing CO2 laser machining parameters, namely, a vertical scanning pathway, 4 W of power, and a feed rate of 9.45 cm/s. Using these improved parameters, we created optical fiber sensors with a core diameter of approximately 400 μm, no obvious optical transmission defects, a numerical aperture of 0.52 ± 0.019, a 0.886 Weibull modulus, and a 1.186 Weibull-shaped parameter. Finally, we used the optical fiber sensor fabricated using the improved parameters to measure the refractive indices of various solutions. The results show that a refractive-index resolution of 1.8 × 10(-4) RIU (linear fitting R2 = 0.954) was achieved for sucrose solutions with refractive indices ranging between 1.333 and 1.383. We also adopted the particle plasmon resonance sensing scheme using the fabricated optical fibers. The results provided additional information, specifically, a superior sensor resolution of 5.73 × 10(-5) RIU, and greater linearity at R2 = 0.999.

No MeSH data available.


Related in: MedlinePlus

Schematic of the experimental setup for creating sensing measurements: (a) function generator (Agilent Inc. Model: 33220A); (b) LED light source (Model: EHP-AX08LS-HA/SUG01-P01, Everlight Inc.); (c) sensing chip; (d) photo diode (Model PD-ET2040, EOT Inc., Traverse, MI, USA); (e) lock-in amplifier (Model 7225, Signal Recovery Inc., Oak Ridge, TN, USA); and (f) computer.
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f14-sensors-13-04067: Schematic of the experimental setup for creating sensing measurements: (a) function generator (Agilent Inc. Model: 33220A); (b) LED light source (Model: EHP-AX08LS-HA/SUG01-P01, Everlight Inc.); (c) sensing chip; (d) photo diode (Model PD-ET2040, EOT Inc., Traverse, MI, USA); (e) lock-in amplifier (Model 7225, Signal Recovery Inc., Oak Ridge, TN, USA); and (f) computer.

Mentions: This study investigated whether the processing parameters selected based on the quality analysis results offer sensing capabilities. The setup of the sensing experiment employed for this study is shown in Figure 14. First, a function generator (Model 33220A, Agilent Inc., Santa Clara, CA, USA) was used to generate a direct current pulse with square waves of a 1-KHz frequency and 1-V voltage to drive the green light-emitting diode (LED) light source (Model EHP-AX08LS-HA/SUG01-P01, Everlight Inc., New Taipei, Taiwan). Next, the total reflection characteristic of optical fiber was used to direct the light into the sensing area for ATR sensing. Subsequently, the optical signal was further directed through the optical fiber to the back-end signal capture device for photoelectric signal conversion and processing. The microfluidic chip was made of poly(methyl methacrylate): PMMA (chip size: 50 × 20 × 8 mm; micro-channel size: 50 × 1 × 0.9 mm) and fabricated using a computer numerical control engraving machine by our group [21]. The sensing fiber was packaged inside the microfluidic chip. The input and output ports of the microfluidic chip were used to infuse the solution flowing through the sensing fiber. The sensing environment involved the injection of various sucrose solution concentrations into a sensing microfluidic chip using a syringe for further sensing testing. For the experiment, we first prepared deionized (DI) water. The relationship between the sucrose concentration and refractive index of 1.333 to 1.383 RIU is shown in Table 1 [7]. After the sensing experiment, to compare our results with those reported in previous literature [13], we calculated the resolution of the sensor. Then, we modified the gold nanoparticles in the sensing area to conduct PPR-sensed environmental refractive index measurements [13]. The gold nanoparticles modified in the optical fiber sensing area were prepared by the study researchers [7].


Fabrication quality analysis of a fiber optic refractive index sensor created by CO2 laser machining.

Chen CH, Yeh BK, Tang JL, Wu WT - Sensors (Basel) (2013)

Schematic of the experimental setup for creating sensing measurements: (a) function generator (Agilent Inc. Model: 33220A); (b) LED light source (Model: EHP-AX08LS-HA/SUG01-P01, Everlight Inc.); (c) sensing chip; (d) photo diode (Model PD-ET2040, EOT Inc., Traverse, MI, USA); (e) lock-in amplifier (Model 7225, Signal Recovery Inc., Oak Ridge, TN, USA); and (f) computer.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3673071&req=5

f14-sensors-13-04067: Schematic of the experimental setup for creating sensing measurements: (a) function generator (Agilent Inc. Model: 33220A); (b) LED light source (Model: EHP-AX08LS-HA/SUG01-P01, Everlight Inc.); (c) sensing chip; (d) photo diode (Model PD-ET2040, EOT Inc., Traverse, MI, USA); (e) lock-in amplifier (Model 7225, Signal Recovery Inc., Oak Ridge, TN, USA); and (f) computer.
Mentions: This study investigated whether the processing parameters selected based on the quality analysis results offer sensing capabilities. The setup of the sensing experiment employed for this study is shown in Figure 14. First, a function generator (Model 33220A, Agilent Inc., Santa Clara, CA, USA) was used to generate a direct current pulse with square waves of a 1-KHz frequency and 1-V voltage to drive the green light-emitting diode (LED) light source (Model EHP-AX08LS-HA/SUG01-P01, Everlight Inc., New Taipei, Taiwan). Next, the total reflection characteristic of optical fiber was used to direct the light into the sensing area for ATR sensing. Subsequently, the optical signal was further directed through the optical fiber to the back-end signal capture device for photoelectric signal conversion and processing. The microfluidic chip was made of poly(methyl methacrylate): PMMA (chip size: 50 × 20 × 8 mm; micro-channel size: 50 × 1 × 0.9 mm) and fabricated using a computer numerical control engraving machine by our group [21]. The sensing fiber was packaged inside the microfluidic chip. The input and output ports of the microfluidic chip were used to infuse the solution flowing through the sensing fiber. The sensing environment involved the injection of various sucrose solution concentrations into a sensing microfluidic chip using a syringe for further sensing testing. For the experiment, we first prepared deionized (DI) water. The relationship between the sucrose concentration and refractive index of 1.333 to 1.383 RIU is shown in Table 1 [7]. After the sensing experiment, to compare our results with those reported in previous literature [13], we calculated the resolution of the sensor. Then, we modified the gold nanoparticles in the sensing area to conduct PPR-sensed environmental refractive index measurements [13]. The gold nanoparticles modified in the optical fiber sensing area were prepared by the study researchers [7].

Bottom Line: Finally, we used the optical fiber sensor fabricated using the improved parameters to measure the refractive indices of various solutions.The results show that a refractive-index resolution of 1.8 × 10(-4) RIU (linear fitting R2 = 0.954) was achieved for sucrose solutions with refractive indices ranging between 1.333 and 1.383.The results provided additional information, specifically, a superior sensor resolution of 5.73 × 10(-5) RIU, and greater linearity at R2 = 0.999.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, National Chung Cheng University, Chiayi 621, Taiwan. saesozj@yahoo.com.tw

ABSTRACT
This study investigates the CO2 laser-stripped partial cladding of silica-based optic fibers with a core diameter of 400 μm, which enables them to sense the refractive index of the surrounding environment. However, inappropriate treatments during the machining process can generate a number of defects in the optic fiber sensors. Therefore, the quality of optic fiber sensors fabricated using CO2 laser machining must be analyzed. The results show that analysis of the fiber core size after machining can provide preliminary defect detection, and qualitative analysis of the optical transmission defects can be used to identify imperfections that are difficult to observe through size analysis. To more precisely and quantitatively detect fabrication defects, we included a tensile test and numerical aperture measurements in this study. After a series of quality inspections, we proposed improvements to the existing CO2 laser machining parameters, namely, a vertical scanning pathway, 4 W of power, and a feed rate of 9.45 cm/s. Using these improved parameters, we created optical fiber sensors with a core diameter of approximately 400 μm, no obvious optical transmission defects, a numerical aperture of 0.52 ± 0.019, a 0.886 Weibull modulus, and a 1.186 Weibull-shaped parameter. Finally, we used the optical fiber sensor fabricated using the improved parameters to measure the refractive indices of various solutions. The results show that a refractive-index resolution of 1.8 × 10(-4) RIU (linear fitting R2 = 0.954) was achieved for sucrose solutions with refractive indices ranging between 1.333 and 1.383. We also adopted the particle plasmon resonance sensing scheme using the fabricated optical fibers. The results provided additional information, specifically, a superior sensor resolution of 5.73 × 10(-5) RIU, and greater linearity at R2 = 0.999.

No MeSH data available.


Related in: MedlinePlus