Enhanced spectral response of π-phase shifted fiber Bragg gratings in closed-loop configuration

2015 ◽  
Vol 40 (9) ◽  
pp. 2124 ◽  
Author(s):  
P. Malara ◽  
C. E. Campanella ◽  
F. De Leonardis ◽  
A. Giorgini ◽  
S. Avino ◽  
...  
Keyword(s):  
Closed Loop ◽  
Spectral Response ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings

Numerical Analysis of Thermal Dependence of the Spectral Response of Polymer Optical Fiber Bragg Gratings

2016 ◽  
Vol 12 (1) ◽  
pp. 85-95 ◽  
Author(s):  
Hisham Hisham
Keyword(s):  
Optical Fiber ◽  
High Stability ◽  
Spectral Response ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Bragg Reflector ◽  
Polymer Optical Fiber ◽  
Thermal Dependence ◽  
Silica Optical Fiber ◽  
Index Modulation

The thermal dependence of the spectral response (i.e. transmission, reflection and time delay ( r) responses) of uniform polymer optical fiber (POF) Bragg gratings has been investigated. In addition to the temperature dependence, the effects of grating strength (kLg) and fiber index modulation ( n) have been investigated. Besides high capability of tunable wavelength due to the unique large and negative thermo-optic coefficient of POF, the spectral response for POF Bragg gratings show high stability and larger spectrum bandwidth with temperature variation compare with the silica optical fiber (SOF) Bragg gratings, especially with the increase of the kLg value. It was found that by increasing kLg, the peak reflectance value increases and the bandwidth of the Bragg reflector become narrower. Also it’s shown by increasing the kLg value, r deceasing significantly and reach its minimum value at the designed wavelength ( B). Furthermore, the r for POF Bragg gratings is less than that for SOF Bragg gratings at the same value of kLg. Also it’s found that the peak reflectivity value increases to around 60% when the n value increases from 1*10-4 to 5*10-4.

A Closed-Loop Interrogation Technique for Multi-Point Temperature Measurement Using Fiber Bragg Gratings

2014 ◽  
Vol 32 (5) ◽  
pp. 971-977 ◽  
Author(s):  
Felipe Walter Dafico Pfrimer ◽  
Marcela Koyama ◽  
Alex Dante ◽  
Elnatan Chagas Ferreira ◽  
Jose Antonio Siqueira Dias
Keyword(s):  
Temperature Measurement ◽  
Closed Loop ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Point Temperature ◽  
Interrogation Technique

scholarly journals High Temperature Effects during High Energy Laser Strikes on Embedded Fiber Bragg Grating Sensors

Sensors ◽  
2019 ◽  
Vol 19 (6) ◽  
pp. 1432
Author(s):  
Michael Ross ◽  
R. Jenkins ◽  
Charles Nelson ◽  
Peter Joyce
Keyword(s):  
High Temperatures ◽  
Spectral Response ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
High Energy ◽  
Carbon Fiber Composites ◽  
Energy Laser ◽  
High Energy Laser ◽  
Thermocouple Temperature ◽  
Heating Test

As the applications of fiber Bragg gratings (FBGs) continue to grow and become more advanced, it becomes necessary to understand their behavior when exposed to high temperatures in unique situations. In these experiments, uniform 1530-nm fiber Bragg gratings and Type K Cr-Al thermocouples were embedded in three-ply carbon fiber composites. A 100 W high energy laser (HEL) heated the composites to high temperatures over timespans less than one second, and FBG spectral data and thermocouple temperature data were collected during each HEL heating test. The data from three high energy laser tests that represent different levels of damage to the FBG are analyzed to explore the spectral response and thermal decay of embedded FBG sensors when exposed to high temperatures over short timespans. Results are compared to a previously proposed power-law model describing the decay of FBGs in bare fiber when held at constant temperatures over much longer timespans.

scholarly journals Optimal parameters for fiber Bragg gratings for sensing applications: a spectral study

2021 ◽  
Vol 3 (6) ◽  
Author(s):  
P. V. Raja Shekar ◽  
D. Madhavi Latha ◽  
Kusum Kumari ◽  
V. G. K. M. Pisipati
Keyword(s):  
Spectral Response ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Main Peak ◽  
Intensity Increase ◽  
List Type ◽  
Maximum Reflectivity ◽  
Sensing Applications ◽  
The Impact ◽  
Index Modulation

Abstract The spectral characteristics viz. reflectivity, bandwidth, and sidelobes’ intensity for uniform and apodized (Gaussian, hyperbolic tangent, apod1, sine, and raised sine) fiber Bragg gratings (FBGs) were studied as a function of grating length and index modulation. The optimal grating length and index modulation to obtain maximum reflectivity and minimum sidelobes were determined, as needed for sensing applications. The impact of various apodization profiles on the spectral response has also been assessed. The results indicate that out of the apodization profiles considered for the study, sine, Gaussian, and raised sine profiles offer the desired output. Article highlights The reflectivity (of main peak) and sidelobes’ intensity increase with grating length and index modulation. The bandwidth decreases with grating length and increases with index modulation. The ideal grating length and index modulation were found to be 5 mm and 0.0008 respectively to obtain maximum reflectivity and minimum intensity for sidelobes. Sine, Gaussian, and raised sine profiles are the best suitable apodization profiles among those considered.

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