scholarly journals Numerical and Experimental Analysis of Matched Filter Interrogation of FBG Sensors with Large Side Lobes

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5522
Author(s):  
Krzysztof Skorupski ◽  
Sławomir Cięszczyk ◽  
Patryk Panas ◽  
Piotr Kisała
Keyword(s):  
Matched Filter ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Side Lobe ◽  
Measurement Range ◽  
Wavelength Shift ◽  
Side Lobe Level ◽  
Matched Filters ◽  
Transfer Characteristics ◽  
High Side

This article presents the effect of fiber Bragg gratings side lobes on interrogation systems consisting of sensor and matched filters. The conducted research shows that high-value side lobe structures applied as sensors and/or filters are characterized by some interesting properties. The paper presents both numerical analysis and experimental verification of the fiber Bragg gratings (FBG) interrogation systems with matched filters for gratings containing high side lobes. Numerical modeling of Bragg structures was performed for two different cases: uniform and inverse apodization. Modification of apodization can change the side lobe reflectance level even above levels found in uniform structures. This is a case not described in the literature, especially in terms of possible applications. Transfer characteristics, i.e., the relationship between power intensity as a function of wavelength shift, were determined. A collection of gratings with spectra corresponding to those analyzed in numerical experiments were fabricated. Next, the transfer characteristics of the interrogation systems containing real FBG were determined. The properties of the proposed systems are described. It has been shown that a significant level of sidebands, which is often the subject of many drawbacks in filtering or telecommunications systems, can be an advantage. It has been demonstrated that a high level of side lobes can be used to increase the measurement range of the FBG sensor interrogation systems. It has been determined numerically and confirmed experimentally that from the point of view of the design of sensor interrogation systems, it is beneficial to combine specific pairs of gratings: one with a spectrum characterized by a low side lobe level and a second one in which the spectrum has very high side lobes.

Novel Flowrate Sensor Based on a Couple of Fiber Bragg Gratings

2011 ◽  
Vol 383-390 ◽  
pp. 6908-6913
Author(s):  
Shu Lian Yang ◽  
Tian Ze Li ◽  
Zhen Mei Li ◽  
Bo Xue Tan ◽  
Kai Zhao
Keyword(s):  
Fiber Bragg Gratings ◽  
Aluminum Foil ◽  
Isosceles Triangle ◽  
Bragg Gratings ◽  
Measurement Range ◽  
Wavelength Shift ◽  
Fiber Grating ◽  
Pressure Sensing ◽  
Cantilever Structure ◽  
The Cross

A novel flowrate sensor based on a couple of fiber Bragg gratings( FBGs) has been proposed, consisting of fiber grating pressure sensing setup and Venturi tube. The expression of relationship between the flowrate and the wavelength shift difference of the FBGs is derived. The pressure that two sides of the cross section of the aluminum foil tube in the pressure sensing setup results in the distortion of an isosceles triangle cantilever structure. The distortion results in the wavelength shift of a couple of FBGs that are mounted at either side of the cantilever. By monitoring the wavelength shift difference of the two FBGs, the flowrate can be obtained. The cross-sensitive problem of the FBGs sensor can be solved by compensating the temperature effect. The preliminary experiments have been carried out, and the results verify the feasibility of the proposed sensor with a measurement range from 8 to 200 mm/s.

Time Analysis of the Wavelength Shift in Fiber Bragg Gratings

2007 ◽  
Vol 25 (11) ◽  
pp. 3580-3588 ◽  
Author(s):  
Paulo de Tarso Neves ◽  
Alexandre de Almeida Prado Pohl
Keyword(s):  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Wavelength Shift ◽  
Time Analysis

scholarly journals Experimental Study on Glaze Icing Detection of 110 kV Composite Insulators Using Fiber Bragg Gratings

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 1834
Author(s):  
Jie Wei ◽  
Yanpeng Hao ◽  
Yuan Fu ◽  
Lin Yang ◽  
Jiulin Gan ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Temperature Compensation ◽  
Fiber Bragg Gratings ◽  
Polar Angle ◽  
Bragg Gratings ◽  
Strain Sensors ◽  
Power Grids ◽  
Wavelength Shift ◽  
Detection Technology ◽  
Load Characteristics

Icing detection of composite insulators is essential for the security and stability of power grids. As conventional methods have met difficulties in harsh weather, a 110 kV composite insulator with embedded Fiber Bragg Gratings (FBGs) was proposed for detecting glaze icing in this paper. FBG temperature compensation sensors in ceramic tubes were adopted for simultaneous measurement of icicle loads and temperature. Then, temperature calibration experiments and simulated icicle load experiments were carried out to obtain temperature and icicle load characteristics of FBGs. The results showed that temperature sensitivities of FBG strain sensors and FBG temperature compensation sensors were 18.16 pm/°C, and 13.18 pm/°C, respectively. Besides, wavelength shifts were linearly related to icicle loads within the polar angle range of −60° to 60°, and the load coefficient of FBG facing the icicle was -34.6 pm/N. In addition, the wavelength shift generated by several icicles was equal to the sum of wavelength shifts generated by each icicle within the polar angle range of −15° to 15°. Finally, icicles can cause wavelength shifts of FBGs within a big shed spacing. The paper provides a novel icing detection technology for composite insulators in transmission lines.

Novel method for the demodulation of wavelength shift of fiber Bragg gratings

2001 ◽  
Author(s):  
Xiaopeng Dong ◽  
Beatrice C. Chu ◽  
Benshun Yi ◽  
K. S. Chiang
Keyword(s):  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Wavelength Shift ◽  
Novel Method

Temperature-stabilized, narrowband tunable fiber-Bragg gratings for matched-filter receiver

2017 ◽  
Author(s):  
Jeffrey M. Roth ◽  
Joseph W. Kummer ◽  
Jeffrey R. Minch ◽  
Bryan G. Malinsky ◽  
Vincent Scalesse ◽  
...  
Keyword(s):  
Matched Filter ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings

scholarly journals Femtosecond Laser Fabricated Apodized Fiber Bragg Gratings Based on Energy Regulation

Photonics ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 110
Author(s):  
Qi Guo ◽  
Zhongming Zheng ◽  
Bo Wang ◽  
Xuepeng Pan ◽  
Shanren Liu ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Suppression Ratio ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Side Lobe ◽  
Energy Regulation ◽  
Fiber Gratings ◽  
Core Diameter ◽  
High Reflectivity ◽  
Side Lobe Suppression

In this paper, an energy regulation method based on the combination of a half-wave plate (HWP) and a polarization beam splitter (PBS) is proposed for the fabrication of apodized fiber gratings, which can effectively improve the side lobe suppression ratio of high-reflectivity fiber Bragg gratings (FBGs) fabricated by femtosecond laser. The apodized FBGs prepared by this method has good repeatability and flexibility. By inputting different types of apodization functions through the program, the rotation speed of the stepping motor can be adjusted synchronously, and then the position of the HWP can be accurately controlled so that the laser energy can be distributed as an apodization function along the axial direction of the fiber. By using the energy apodization method, the gratings with a reflectivity of 75% and a side lobe suppression ratio of 25 and 32 dB are fabricated in the fiber with a core diameter of 9 and 4.4 μm, respectively. The temperature and strain sensitivities of the energy-apodized fiber gratings with a core diameter of 4.4 μm are 10.36 pm/°C and 0.9 pm/με, respectively. The high-reflectivity gratings fabricated by this energy apodization method are expected to be used in high-power narrow-linewidth lasers and wavelength division multiplexing (WDM) systems.

TUNABLE ERBIUM-DOPED FIBER RING LASER BASED ON A NOVEL THERMAL TUNING SCHEME OF FIBER BRAGG GRATINGS

2010 ◽  
Vol 24 (10) ◽  
pp. 963-969 ◽  
Author(s):  
QUN HAN ◽  
ZHAOXIA SHENG
Keyword(s):  
Ring Laser ◽  
Thermal Sensitivity ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Wavelength Shift ◽  
Fiber Ring Laser ◽  
Fiber Ring ◽  
Erbium Doped ◽  
Good Repeatability ◽  
Thermal Tuning

A novel thermal tuning technique of fiber Bragg gratings is proposed. With this technique, the thermal sensitivity of FBG can now be flexibly designed. The proposed technique is used in an erbium-doped fiber ring laser. A wavelength shift of 6.8 nm is obtained with a temperature change of only 20°C, which corresponds to a thermal sensitivity of 0.34 nm/°C. The 3 dB linewidth of the laser is less than 0.1 nm in the whole tuning range. The threshold and slope efficiency of the laser are 7.9 mW and 18.6%, respectively. The laser tuning has good linearity and good repeatability.

scholarly journals Sensor Based on Multiple Fiber Bragg Gratings for Diameter Measurement

2020 ◽  
Vol 238 ◽  
pp. 12013
Author(s):  
Victor Cardoso ◽  
Paulo Caldas ◽  
M. Giraldi R. Thereza ◽  
Orlando Frazão ◽  
Claudio Carvalho ◽  
...  
Keyword(s):  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Wavelength Shift ◽  
Experimental Setup ◽  
3D Printer ◽  
Diameter Measurement ◽  
Diameter Variation

A method based on multiple Fiber Bragg Gratings (FBG) and a structure fabricated using a 3D printer for diameter measurement is proposed and experimentally demonstrated. The sensor is easily developed inserting the FBG on the structure and fixing the FBG in two points. Due to this arrangement, when the diameter is reduced a force is applied on the sensor and this causes a wavelength shift. The study is divided in two steps using one experimental setup. At first, each FBG response is independently evaluated concerning the diameter variation and after that, the FBGs are evaluated together. The results demonstrated that the structure can be used as a way to monitor the diameter variation in some applications.

Sign in / Sign up

Export Citation Format

Share Document