scholarly journals Fiber Bragg Grating with Enhanced Cladding Modes Inscribed by Femtosecond Laser and a Phase Mask

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7004
Author(s):  
Weijia Bao ◽  
Shen Liu ◽  
Wenjie Feng ◽  
Yiping Wang

In this paper, we demonstrate a fiber Bragg grating (FBG) with a wide range and a comb with continuous cladding mode resonances inscribed in non-photosensitive single mode fibers using a femtosecond laser and a phase mask. The FBG is inscribed in the core and cladding, exciting a series of cladding modes in transmission. The birefringence induced by this FBG structure offers significant polarization-dependence for cladding modes, thus allowing the vector fiber twist to be perceived. By measuring the peak-to-peak differential intensity of orthogonally polarized cladding mode resonances, the proposed sensor presents totally opposite intensity response in the anticlockwise direction for the torsion angle ranging from −45° to 45°. The cladding mode comb approximately covers wavelengths over the O-, E-, S-, and C-bands in transmission. The cutoff cladding mode of air can be observed in the spectrum. Thus, the sensible refractive index range is estimated to be from 1.00 to 1.44. Temperature responsivity of the grating is also characterized. The proposed device potentially provides new solutions to the various challenges of physical vector and bio-chemical parameters sensing.

2022 ◽  
Vol 12 (2) ◽  
pp. 886
Author(s):  
Hun-Kook Choi ◽  
Young-Jun Jung ◽  
Bong-Ahn Yu ◽  
Jae-Hee Sung ◽  
Ik-Bu Sohn ◽  
...  

This paper demonstrates the fabrication of radiation-resistant fiber Bragg grating (FBG) sensors using infrared femtosecond laser irradiation. FBG sensors were written inside acrylate-coated fluorine-doped single-mode specialty optical fibers. We detected the Bragg resonance at 1542 nm. By controlling the irradiation conditions, we improved the signal strength coming out from the FBG sensors. A significant reduction in the Bragg wavelength shift was detected in the fabricated FBG sensors for a radiation dose up to 105 gray, indicating excellent radiation resistance capabilities. We also characterized the temperature sensitivity of the radiation-resistant FBG sensors and detected outstanding performance.


2019 ◽  
Vol 9 (15) ◽  
pp. 3107 ◽  
Author(s):  
Carlo Molardi ◽  
Tiago Paixão ◽  
Aidana Beisenova ◽  
Rui Min ◽  
Paulo Antunes ◽  
...  

The characterization of Fiber Bragg Grating (FBG) sensors on a high-scattering fiber, having the core doped with MgO nanoparticles for polarization-dependent temperature sensing is reported. The fiber has a scattering level 37.2 dB higher than a single-mode fiber. FBGs have been inscribed by mean of a near-infrared femtosecond laser and a phase mask, with Bragg wavelength around 1552 nm. The characterization shows a thermal sensitivity of 11.45 pm/°C. A polarization-selective thermal behavior has been obtained, with sensitivity of 11.53 pm/°C for the perpendicular polarization (S) and 11.08 pm/°C for the parallel polarization (P), thus having 4.0% different sensitivity between the two polarizations. The results show the inscription of high-reflectivity FBGs onto a fiber core doped with nanoparticles, with the possibility of having reflectors into a fiber with tailored Rayleigh scattering properties.


Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5938
Author(s):  
Xinran Dong ◽  
Li Zeng ◽  
Dongkai Chu ◽  
Xiaoyan Sun

A hybrid sensing configuration for simultaneous measurement of strain and temperature based on fiber Bragg grating (FBG) written in an offset multimode fiber (MMF) interferometer using femtosecond laser pulse is proposed and demonstrated. A Mach–Zehnder interferometer is formed by splicing a section of MMF between two single-mode fibers (SMFs) and a high interference fringe of up to 15 dB is achieved. The sensing experimental results show a strain sensitivity of −1.17 pm/με and 0.6498 pm/με for the dip of MZI and Bragg peak, while a temperature sensitivity of 42.84 pm/°C and 19.96 pm/°C is measured. Furthermore, the matrix analysis has found that the strain and temperature resolution of the sensor are as high as ±12.36 με and ±0.35 °C, respectively. In addition, the sensor has merits of simple fabrication, good spectral quality, and high resolution, which shows attractive potential applications in dual-parameter sensing.


2018 ◽  
Vol 8 (12) ◽  
pp. 2616 ◽  
Author(s):  
Wen Zhang ◽  
Lianqing Zhu ◽  
Mingli Dong ◽  
Xiaoping Lou ◽  
Feng Liu

A temperature fiber sensor based on tapered fiber Bragg grating (tapered FBG) fabricated by femtosecond laser has been proposed and realized with good reproducibility. Firstly, the fiber taper with 25 μm diameter and 1000 μm length is fabricated by arc-discharge elongation using two standard single-mode fibers. Secondly, two first-order FBGs are fabricated in tapered and non-tapered fiber regions for comparison. Both FBGs are point-by-point direct-written by femtosecond laser, and the grating lengths are 1000 μm. Thirdly, a temperature experiment is performed using a heating chamber, and experimental results show that in the range of 30~350 °C, the temperature sensitivity of the tapered FBG has increased from 11.0 pm/°C to 12.3 pm/°C. The tapered FBG proposed here can be further configured for sensing other parameters in physical, chemical, and biomedical applications.


2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Jiali An ◽  
Tao Liu ◽  
Yongxing Jin

A temperature-insensitive fiber optic vibration sensor based on the tilted fiber Bragg grating (TFBG) is presented. The sensing head is formed by insertion of a small section of MMF between a single-mode fiber and the TFBG. The reflection light from this tilted fiber Bragg grating includes two parts: the reflected Bragg mode and the cladding modes. The cladding modes were coupled back into the core mode as a function of the multimode fiber. The power of the cladding modes is sensitive to vibration, so the external vibration measurement can be obtained through the cladding mode average output power. Experiment results show that the root mean square (RMS) of the detection error of the average power was 0.01 μW within the temperature range from 20 to 70°C, so it is proved to be temperature independent; its frequency response has been tested to 1 KHz.


2009 ◽  
Author(s):  
K. Kalli ◽  
T. Geernaert ◽  
C. Koutsides ◽  
M. Komodromos ◽  
T. Nasilowski ◽  
...  

2016 ◽  
Vol 86 ◽  
pp. 236-241 ◽  
Author(s):  
Yajun Jiang ◽  
Yuan Yuan ◽  
Jian Xu ◽  
Dexing Yang ◽  
Dong Li ◽  
...  

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