A temperature sensing method based on a liquid-filled hollow-core annular fiber grating

A fiber grating and sensing method technology, applied in the field of sensors, can solve the problems of poor stability of the measurement system of the ring-type optical fiber temperature sensor, and achieve the effects of compact structure, good stability and small size

Active Publication Date: 2020-03-24
NORTHEASTERN UNIV LIAONING
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Problems solved by technology

[0003] The purpose of the present invention is to overcome the disadvantages of the above-mentioned tapered optical fiber structure temperature sensor mechanical properties and service life, and the poor stability of the ring type optical fiber temperature sensor measurement system, and propose a high-sensitivity temperature sensor based on liquid-filled hollow-core annular fiber gratings. Sensing method, which has the advantages of compact structure, good mechanical properties, good stability and high sensitivity

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  • A temperature sensing method based on a liquid-filled hollow-core annular fiber grating
  • A temperature sensing method based on a liquid-filled hollow-core annular fiber grating
  • A temperature sensing method based on a liquid-filled hollow-core annular fiber grating

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Embodiment 1

[0035] A high-sensitivity temperature sensing method based on a liquid-filled hollow-core annular fiber grating, comprising the steps of:

[0036] Step 1: Fabricate a hollow-core ring-shaped optical fiber by chemical vapor deposition and optical fiber drawing equipment. Hollow-core ring fibers have a high-refractive-index ring to transmit light within the high-refractive-index ring. Schematic diagram of the end face structure and refractive index distribution of the grating region of the hollow-core ring fiber figure 1 shown. The inner diameter of the ring core of the hollow core ring fiber a 1 = 1μm, cladding radius a 3 =62.5μm, the high refractive index ring material is Corning SMF-28 core material, and its refractive index n 2 =1.4681, the cladding material is pure silica, its refractive index n 3 =1.444, the relative material refractive index difference between the high refractive index ring and the cladding is 16‰, this material has the advantages of easy acquisition...

Embodiment 2

[0047] A high-sensitivity temperature sensing method based on a liquid-filled hollow-core annular fiber grating, comprising the steps of:

[0048] Step 1, with embodiment 1;

[0049] Step 2: Through unilateral UV exposure of the hollow-core ring-shaped fiber filled with opaque liquid, the periodic refractive index modulation of the upper half-ring is realized, and a hollow-core ring-shaped fiber with an asymmetric grating is made, and the grating period Λ =220μm, the number of grating periods N is 35; the refractive index modulation value Δn=2.8×10 -4 , the corresponding grating length L=0.77cm, the temperature is 25°C, namely n 1 = 1.444, the mode conversion rate is as high as 92.43%. Since the asymmetric fiber grating breaks the circular symmetry of the fiber structure, it can realize the conversion between the angle and non-same-order modes in the ring;

[0050] Step 3: Fill the hollow core of the hollow-core annular fiber grating with a refractive index matching liquid b...

Embodiment 3

[0056] A high-sensitivity temperature sensing method based on a liquid-filled hollow-core annular fiber grating, comprising the steps of:

[0057] Step 1, with embodiment 1;

[0058] Step 2: Through unilateral UV exposure of the hollow-core ring-shaped fiber filled with opaque liquid, the periodic refractive index modulation of the upper half-ring is realized, and a hollow-core ring-shaped fiber with an asymmetric grating is made, and the grating period Λ =235μm, number of grating periods N=45; refractive index modulation value Δn=2.9×10 -4 , the corresponding grating length L=1.058cm, the temperature is 25°C, namely n 1 = 1.444, the mode conversion rate is as high as 99.44%. Since the asymmetric fiber grating breaks the circular symmetry of the fiber structure, it can realize the conversion between the angle and non-same-order modes in the ring;

[0059] Step 3: Fill the hollow core of the hollow-core annular fiber grating with a refractive index matching liquid by capillar...

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Abstract

A temperature sensing method based on a liquid-filled hollow-core annular fiber grating. A long-period fiber grating is engraved on the upper half ring of the hollow-core annular fiber, and this asymmetric long-period fiber grating divides the incident line polarization fundamental mode HE 11x converted to TE 01 mode and HE 21x model. input HE 11x Due to the loss of light energy, the mode forms a resonance valley in its transmission spectrum, and the center wavelength of the resonance valley is the resonance wavelength. The hollow core of the hollow-core annular fiber is filled with a refractive index matching liquid with a high thermo-optic coefficient. When the ambient temperature changes, the refractive index value of the refractive index matching liquid changes, causing the grating resonance wavelength position to change. The temperature sensing system consists of a wide-spectrum light source, an input single-mode fiber, a polarization-maintaining fiber, a hollow-core annular fiber grating, an output single-mode fiber and a spectrum analyzer. As the temperature increases, the grating resonance wavelength increases linearly. This method has the advantages of good stability and high sensitivity.

Description

technical field [0001] The invention belongs to the technical field of sensors, and relates to a temperature sensing method based on a liquid-filled hollow-core annular optical fiber grating. Background technique [0002] Due to its small size, high sensitivity, no electromagnetic interference, and chemical corrosion resistance, the research on optical fiber temperature sensors has attracted more and more attention from scholars. At present, a variety of fiber optic temperature sensors have been reported, such as fiber grating temperature sensors, side-polished fiber temperature sensors, fiber optic fluorescence temperature sensors, fiber optic ring temperature sensors, fiber optic interferometer temperature sensors, etc. The temperature measurement sensitivity of ordinary fiber optic sensors is low, because its temperature sensing mechanism mainly relies on the thermo-optic properties of silica materials, and silica materials have low thermo-optic coefficients. In recent y...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01K11/32G01K11/3206
CPCG01K11/3206
Inventor 赵勇夏凤胡海峰
Owner NORTHEASTERN UNIV LIAONING
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