Composite fiber grating sensor and dual-parameter measurement method of refractive index and temperature

A technology of grating sensor and composite optical fiber, which is applied in thermometers, measuring devices, measuring heat, etc., can solve problems such as the inability to realize dual-parameter measurement of temperature and refractive index, and achieve the effects of reliable performance, reduced calculation amount, and high temperature sensitivity

Active Publication Date: 2019-05-03
TIANJIN UNIV
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  • Abstract
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AI Technical Summary

Problems solved by technology

However, due to the cross-sensitivity of refractive index and temperature, it is impossible to achieve dual-parameter measurement of temperature and refractive index by using either tilted fiber Bragg gratings or long-period fiber gratings alone.

Method used

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  • Composite fiber grating sensor and dual-parameter measurement method of refractive index and temperature
  • Composite fiber grating sensor and dual-parameter measurement method of refractive index and temperature
  • Composite fiber grating sensor and dual-parameter measurement method of refractive index and temperature

Examples

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Embodiment 1

[0031] Example 1: The structure and production of a composite fiber grating sensor for dual-parameter measurement of refractive index and temperature

[0032] like figure 1 As shown, the sensor writes the long-period grating and the tilted grating successively at the same position of the fiber. First, a carbon dioxide laser is used to write long-period gratings by point-by-point writing method. The specific process is that the laser beam output by the laser is focused by a cylindrical mirror and exposed on the side of the single-mode fiber 1, and a grating stripe is written in the fiber core 2. Afterwards, the single-mode fiber 1 is moved horizontally by a distance of one grating period to expose the next point, and this process is repeated until all the grating stripes are written. The grating period is 600 microns. The grating length is 15 mm. During the writing process, the optical single-mode fiber 1 is pre-stretched in the axial direction, and the tension is 0.5 Newton...

Embodiment 3

[0033] Example 3: An experimental system and demodulation of a composite fiber grating sensor for dual-parameter measurement of refractive index and temperature

[0034] The light emitted by the scanning laser enters the composite fiber grating sensor, and then the outgoing light 6 enters the light wave measurement system, figure 2 Shown is the transmission spectrum acquired by the lightwave measurement system. Use the low-pass filtering method to separate the transmission spectrum, and obtain the long-period grating spectrum and the tilted grating spectrum respectively, such as image 3 shown. in image 3 (a) is the extracted long-period grating spectrum, image 3 (b) is the extracted tilted grating spectrum. The fabricated composite fiber grating sensor was measured for refractive index at room temperature, Figure 4 Shown is the transmission spectrum as the refractive index increases from 1.3782 to 1.4477 in glycerol solution, where Figure 4 (a) is the original spectr...

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Abstract

The invention discloses a composite fiber grating sensor and the dual-parameter measurement method of a refractive index and a temperature. A sensor structure comprises a single mode fiber (1) and a single mode fiber core (2). The single mode fiber core (2) is provided with a hybrid grating formed by a long period grating (3) and an inclined grating (4) along a horizontal direction. Incident light(5) is emitted into the hybrid grating, and then emergent light (6) enters into an optical wave measuring system. The wavelength offset of an inclined grating refractive index measurement factor is acquired, and then an actual sensitivity value is obtained through the inversion of a sensitivity coefficient. Then, the actual sensitivity value is used to compensate the wavelength shift caused by arefractive index in the dual-parameter measurement factor of the long period grating, and a measured temperature is acquired, and the dual-parameter measurement of the refractive index and the temperature is realized. Two parameters can be measured simultaneously, the structure is simple, a calculated amount is reduced, and the advantage of the high refractive index sensitivity in a traditional long period grating and the advantage of high temperature sensitivity in the inclined grating are possessed simultaneously.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing, and in particular relates to an all-fiber refractive index and temperature dual-parameter sensor and a measuring method based on the fiber grating theory. Background technique [0002] Optical fiber grating sensing system is a system that uses light as the carrier and optical fiber as the medium, and uses optical fiber grating sensors with the advantages of light weight, thin diameter, corrosion resistance, strong multiplexing ability, and anti-electromagnetic interference for sensing and measurement. The reflection wavelength of the fiber grating sensor is related to the physical parameters such as stress and strain, temperature and refractive index acting on the sensor. By measuring the reflection wavelength of the sensor, the physical parameters acting on the sensor can be measured. Compared with traditional sensing technology, optical fiber sensing technology has the characteris...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/43G01K11/32G01K11/3206
Inventor 江俊峰刘铁根张学智樊晓军刘琨王双李雨晴褚悦徐棒田蒋磊
Owner TIANJIN UNIV
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