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.

Monitoring of Microorganisms Growth Process Based on Fiber Bragg Grating Biosensor

2011 ◽  
Vol 84-85 ◽  
pp. 586-589
Author(s):  
Ming Fu Zhao ◽  
De Yi Huang ◽  
Lei Zi Jiao ◽  
Xue Mei Cao ◽  
Xi Han
Keyword(s):  
Refractive Index ◽  
Fiber Bragg Grating ◽  
Nonlinear Behavior ◽  
Bragg Grating ◽  
Wavelength Shift ◽  
Refractive Index Sensitivity ◽  
Bragg Wavelength ◽  
Index Changes ◽  
Index Sensitivity ◽  
The Relationship

The low refractive index sensing principle of the fiber Bragg grating (FBG) was analyzed theoretically, the temperature compensation scheme corresponding to the theoretical model was established. A single-end etched FBG was designed and fabricated for simultaneous measurement of temperature and refractive index. The experimental results demonstrated that the Bragg wavelength shift exhibits a nonlinear behavior with the temperature and yeast refractive index changes. The temperature change to the influence of the sensor was eliminated by numerical analysis, and then the relationship between the Bragg wavelength shift and the yeast refractive index is linear, the sensor yeast refractive index sensitivity of 5.42nm/riu was obtained.

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.

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.

Numerical investigation of gold plated single-core photonic crystal fiber-based refractive index sensor

2021 ◽  
Author(s):  
Monika Kiroriwal ◽  
Poonam Singal
Keyword(s):  
Refractive Index ◽  
Photonic Crystal ◽  
Photonic Crystal Fiber ◽  
Refractive Index Sensor ◽  
Geometrical Parameters ◽  
Refractive Index Sensitivity ◽  
Crystal Fiber ◽  
Simple Geometry ◽  
Bio Imaging ◽  
Index Sensitivity

Surface plasmon resonance (SPR)-based single-core photonic crystal fiber (PCF) biosensor is investigated with external gold coating. All the geometrical parameters such as a gold layer, an analyte layer, a lattice period and cladding air holes are optimized to enhance the sensing ability of the sensor by introducing the finite element method. The designed sensor is able to achieve the highest amplitude sensitivity (AS) of 2258.95 RIU[Formula: see text] with an acceptable refractive index sensitivity (RIS) of 6000 nm/RIU over the analyte refractive index (ARI) span of 1.31–1.40. This sensor can detect a slight index alteration in the sensing medium using a resolution of [Formula: see text] and a high figure of merit (FOM) of 79.01. With the enhanced modal behavior with simple geometry, the resulting sensor can be suitable for real-time monitoring in biological, biochemical and bio-imaging applications.

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