A Temperature Fiber Sensor Based on Tapered Fiber Bragg Grating Fabricated by Femtosecond Laser

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.

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Femtosecond-Laser-Assisted Fabrication of Radiation-Resistant Fiber Bragg Grating Sensors

Applied Sciences ◽

10.3390/app12020886 ◽

2022 ◽

Vol 12 (2) ◽

pp. 886

Author(s):

Hun-Kook Choi ◽

Young-Jun Jung ◽

Bong-Ahn Yu ◽

Jae-Hee Sung ◽

Ik-Bu Sohn ◽

...

Keyword(s):

Femtosecond Laser ◽

Fiber Bragg Grating ◽

Optical Fibers ◽

Coming Out ◽

Single Mode ◽

Femtosecond Laser Irradiation ◽

Bragg Grating ◽

Wavelength Shift ◽

Radiation Resistant ◽

Fbg Sensors

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.

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Highly Sensitive Dual Parameter Sensor Based on a Hybrid Structure with Multimode Interferometer and Fiber Bragg Grating Fabricated by Femtosecond Laser

Sensors ◽

10.3390/s21175938 ◽

2021 ◽

Vol 21 (17) ◽

pp. 5938

Author(s):

Xinran Dong ◽

Li Zeng ◽

Dongkai Chu ◽

Xiaoyan Sun

Keyword(s):

Femtosecond Laser ◽

Fiber Bragg Grating ◽

Single Mode ◽

Hybrid Structure ◽

Matrix Analysis ◽

Attractive Potential ◽

Bragg Grating ◽

Highly Sensitive ◽

The Matrix ◽

Potential Applications

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.

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

Sensors ◽

10.3390/s20247004 ◽

2020 ◽

Vol 20 (24) ◽

pp. 7004

Author(s):

Weijia Bao ◽

Shen Liu ◽

Wenjie Feng ◽

Yiping Wang

Keyword(s):

Femtosecond Laser ◽

Fiber Bragg Grating ◽

Single Mode ◽

Phase Mask ◽

Bragg Grating ◽

Chemical Parameters ◽

Anticlockwise Direction ◽

Wide Range ◽

Intensity Response ◽

Cladding Mode

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.

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