scholarly journals Temperature Self-Compensated Refractive Index Sensor Based on Fiber Bragg Grating and the Ellipsoid Structure

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5211 ◽  
Author(s):  
Binbin Yan ◽  
Lei Sun ◽  
Yanhua Luo ◽  
Liwei Yang ◽  
Haifeng Qi ◽  
...  
Keyword(s):  
Refractive Index ◽  
Fiber Bragg Grating ◽  
Resonant Peak ◽  
Bragg Grating ◽  
Wavelength Shift ◽  
Refractive Index Sensor ◽  
Average Sensitivity ◽  
Surrounding Refractive Index ◽  
Index Unit ◽  
Sensing Performance

In this paper, a temperature self-compensated refractive index sensor based on fiber Bragg grating (FBG) and the ellipsoid structure is demonstrated. The ellipsoid can excite the cladding modes and recouple them into the fiber core. Two well-defined wavelength bands are observed in the reflection spectrum of the proposed sensor, i.e., the Bragg resonant peak and the cladding resonant peaks. By measuring the wavelength shift of the cladding resonant peak, the surrounding refractive index (SRI) can be determined, and the wavelength shift of the Bragg resonant peak can be used as a reliable reference to self-compensate the temperature variation (temperature sensitivity of 10.76 pm/°C). When the SRI changes from 1.3352 to 1.3722, the cladding resonant peak redshifts linearly with an average sensitivity of 352.6 pm/RIU (refractive index unit). When the SRI changes from 1.3722 to 1.4426, an exponential redshift is observed with a maximum sensitivity of 4182.2 pm/RIU. Especially, the sensing performance is not very reliant on the distance between the FBG and the ellipsoid, greatly improving the ease of the fabrication.

Chemical Sensors Based on Fiber Bragg Grating

2011 ◽  
Vol 84-85 ◽  
pp. 582-585 ◽  
Author(s):  
Ming Fu Zhao ◽  
De Yi Huang ◽  
Bin Zhou ◽  
Lei Zi Jiao
Keyword(s):  
Refractive Index ◽  
Fiber Bragg Grating ◽  
Chemical Sensor ◽  
Bragg Grating ◽  
Wavelength Shift ◽  
Bragg Wavelength ◽  
Chemical Substances ◽  
Fbg Sensor ◽  
Surrounding Refractive Index ◽  
The Relationship

In this paper, measurement method for the refractive index of chemical substances based on fiber Bragg grating (FBG) sensor was proposed. The relation between Bragg wavelength shift and surrounding refractive index (SRI) was analyzed theoretically and experimentally. The SRI sensitivity of the chemical sensor could be enhanced by reducing the cladding thickness of the FBG using hydrofluoric acid (HF) solution etching process. The experimental results indicated that the variation of Bragg wavelength increased as the SRI increased. In the low SRI region, the relationship between the Bragg wavelength shift and the change of the SRI was approximately linear.

scholarly journals Wavelet-Based Demodulation of Multimode Etched Fiber Bragg Grating Refractive Index Sensor

Sensors ◽  
2018 ◽  
Vol 19 (1) ◽  
pp. 39 ◽  
Author(s):  
Takhmina Ayupova ◽  
Marzhan Sypabekova ◽  
Carlo Molardi ◽  
Aliya Bekmurzayeva ◽  
Madina Shaimerdenova ◽  
...  
Keyword(s):  
Refractive Index ◽  
Spectral Density ◽  
Fiber Bragg Grating ◽  
Bragg Grating ◽  
Wavelength Shift ◽  
Refractive Index Sensor ◽  
Refractive Index Sensitivity ◽  
Index Sensitivity ◽  
Fiber Thickness ◽  
Refractive Index Detection

Etched fiber Bragg grating (EFBG)-based sensors are used as evanescent field sensors for refractive index detection. When the fiber thickness is thin and the refractive index sensitivity increases, the number of propagating modes increases, resulting in a spectral enlargement that complicates the interrogation of the sensor. In this work, we present a method to analyze the spectrum of a multimode etched fiber Bragg grating (MMEFBG) in the wavelet domain, which analyzes the amount of spectral density independently from the peak reflectivity value. The proposed interrogation method permits defining the integral of the spectral density as a novel and unconventional estimator. With respect to the conventional estimators based on wavelength shift, this estimator can better exploit the larger amount of information given by the spectral enlargement typical of multimode behavior. Results were obtained by etching an MMEFBG in hydrofluoric acid and using water/sucrose mixtures to evaluate the refractive index sensitivity, validating the interrogation method.

Refractive Index Sensing Based on a Fiber Bragg Grating with Micro-Holes

2011 ◽  
Vol 495 ◽  
pp. 194-197
Author(s):  
Min Wei Yang ◽  
D. N. Wang ◽  
C. R. Liao
Keyword(s):  
Refractive Index ◽  
Fiber Bragg Grating ◽  
Intensity Variation ◽  
Bragg Grating ◽  
Wavelength Shift ◽  
Refractive Index Sensor ◽  
Refractive Index Sensitivity ◽  
Femtosecond Laser Micromachining ◽  
Micro Holes ◽  
Index Sensitivity

A refractive index sensor based on single fiber Bragg grating with multiple micro-holes is proposed. The micro-holes are drilled by use of femtosecond laser micromachining. The key feature of the sensor is that a simultaneous and independent refractive index and temperature sensing measurement can be implemented by simply detecting the grating resonant wavelength shift and its intensity variation, respectively. The refractive index sensitivity obtained is 29.50 dB/RIU (refractive index unit), within the refractive index range between 1.30 and 1.45.

scholarly journals Etched Fiber Bragg Grating Biosensor Functionalized with Aptamers for Detection of Thrombin

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4298 ◽  
Author(s):  
Aliya Bekmurzayeva ◽  
Kanat Dukenbayev ◽  
Madina Shaimerdenova ◽  
Ildar Bekniyazov ◽  
Takhmina Ayupova ◽  
...  
Keyword(s):  
Refractive Index ◽  
Fiber Bragg Grating ◽  
Chemical Vapor ◽  
Bragg Grating ◽  
Clinical Settings ◽  
Long Period Grating ◽  
Bragg Wavelength ◽  
Sensing System ◽  
Index Unit

A biosensor based on an etched Fiber Bragg Grating (EFBG) for thrombin detection is reported. The sensing system is based on a Fiber Bragg Grating (FBG) with a Bragg wavelength of 1550 nm, wet-etched in hydrofluoric acid (HF) for ~27 min, to achieve sensitivity to a refractive index (RI) of 17.4 nm/RIU (refractive index unit). Subsequently, in order to perform a selective detection of thrombin, the EFBG has been functionalized with silane-coupling agent 3-(aminopropyl)triethoxysilane (APTES) and a cross-linker, glutaraldehyde, for the immobilization of thrombin-binding aptamer. The biosensor has been validated for thrombin detection in concentrations ranging from 10 nM to 80 nM. The proposed sensor presents advantages with respect to other sensor configurations, based on plasmonic resonant tilted FBG or Long Period Grating (LPG), for thrombin detection. Firstly, fabricating an EFBG only requires chemical etching. Moreover, the functionalization method used in this study (silanization) allows the avoidance of complicated and expensive fabrications, such as thin film sputtering or chemical vapor deposition. Due to their characteristics, EFBG sensors are easier to multiplex and can be used in vivo. This opens new possibilities for the detection of thrombin in clinical settings.

scholarly journals Tilted Fiber Bragg Grating Sensor Using Chemical Plating of a Palladium Membrane for the Detection of Hydrogen Leakage

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4478 ◽  
Author(s):  
Jiachen Yu ◽  
Zhenlin Wu ◽  
Xin Yang ◽  
Xiuyou Han ◽  
Mingshan Zhao
Keyword(s):  
Fiber Bragg Grating ◽  
Low Cost ◽  
Hydrogen Sensor ◽  
Bragg Grating ◽  
Wavelength Shift ◽  
Cross Sensitivity ◽  
Chemical Plating ◽  
Palladium Membrane ◽  
Surrounding Refractive Index ◽  
The Cross

A tilted fiber Bragg grating (TFBG) hydrogen sensor coated with a palladium (Pd) membrane by the electroless plating method is proposed in this paper. A uniform layer of Pd metal is fabricated in aqueous solutions by the chemical coating method, which is used as the sensitive element to detect the change of the surrounding refractive index (SRI) caused by hydrogen absorption. The change in SRI causes an unsynchronized change of the cladding modes and the Bragg peak in the TFBG transmission spectrum, thereby eliminating the cross-sensitivity due to membrane expansion and is able to simultaneously monitor the presence of cracks in the pipe, as well as the hydrogen leakage. By subtracting the wavelength shift caused by fiber expansion, the change of SRI, i.e., the information from the H2 level, can be separately obtained. The drifted wavelength is measured for the H2 concentration below the hydrogen explosion limit between 1% and 4%. The chemical-based coating has the advantages of a low cost, a simple operation, and being suitable for coating on long fiber structures. The proposed sensor is able to detect the H2 signal in 5 min at a 1% H2 concentration. The proposed sensor is proved to be able to monitor the hydrogen level without the cross-sensitivity of temperature variation and expansion strains, so could be a good candidate for security applications in industry.

Numerical analyses for thinned fiber Bragg grating under uneven surrounding refractive index environment

2011 ◽  
Author(s):  
Bin-bin Luo ◽  
Ming-fu Zhao ◽  
Xiao-jun Zhou ◽  
De-yi Huang ◽  
Shao-fei Wang ◽  
...  
Keyword(s):  
Refractive Index ◽  
Fiber Bragg Grating ◽  
Numerical Analyses ◽  
Bragg Grating ◽  
Surrounding Refractive Index

scholarly journals Modeling and Simulation of Fiber Bragg Grating (Fbg) as A Strain Sensor

2017 ◽  
Vol 10 (2) ◽  
pp. 260-263 ◽  
Author(s):  
Muhammad Bin Jalil
Keyword(s):  
Refractive Index ◽  
Fiber Bragg Grating ◽  
Spectral Response ◽  
Grating Period ◽  
Applied Strain ◽  
Bragg Grating ◽  
Wavelength Shift ◽  
Fiber Grating ◽  
Spectral Reflectivity ◽  
Maximum Reflectivity

This study presents the modelling, simulation, and characterization of the Fiber Bragg grating (FBG) on maximum reflectivity, bandwidth, the effect of applied strain to the wavelength shift, ʎB and sensitivity of the wavelength shift with strain for optical sensing system. In this study, a commercial FBG with the center wavelength of 1550nm is used in order to measure the spectral response of FBG to strain. The parameters used in these simulations are the fiber grating length, L ranging from 1 to 10mm, the changes in refractive index, ∆n from 0.0002 to 0.0020, the effective refractive index, is 1.46 and the grating period of FBG,Λ for 530nm in the performance of FBG. The bandwidth and spectrum reflectivity are analyzed from the variation of refractive index and grating length. Simulations on the FBG are carried out using OriginPro 2016 and Microsoft Excel 2010 software. The Excel sheet is used to generate data and the OriginPro 2016 is used to generate the graphs. The results obtained indicates the variation in grating length and refractive index affect the spectral reflectivity and the bandwidth. In addition, results obtained show that the changes in the Bragg wavelength are due to an increase in length of the grating region which due to the applied strain.

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