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A Method for Simultaneous Sensing of Temperature, Strain and Refractive Index Using a Single Fiber Bragg Grating

A Bragg grating and single optical fiber technology, which is applied in the direction of transmitting sensing components, converting sensor output, instruments, etc. by using optical devices, can solve the problem of simultaneous sensing of single optical fiber sensors and achieve good consistency, simple structure, high efficiency effect

Inactive Publication Date: 2019-03-01
NORTHWESTERN POLYTECHNICAL UNIV
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Problems solved by technology

[0005] In order to solve the problem that the current single optical fiber sensor is difficult to simultaneously sense the three parameters of temperature, strain and refractive index, the present invention proposes a method for simultaneously sensing temperature, strain and refractive index by using a single FBG. High sensitivity, easy signal demodulation, easy to manufacture sensor head, good consistency, high efficiency, and has the advantages of simple structure, high mechanical strength and no special packaging

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  • A Method for Simultaneous Sensing of Temperature, Strain and Refractive Index Using a Single Fiber Bragg Grating
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  • A Method for Simultaneous Sensing of Temperature, Strain and Refractive Index Using a Single Fiber Bragg Grating

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Embodiment Construction

[0023] Now in conjunction with embodiment, accompanying drawing, the present invention will be further described:

[0024] The implementation steps of using a single FBG to realize simultaneous sensing of temperature, strain and refractive index are as follows: figure 1 Shown:

[0025] Step 1: Writing FBGs in few-mode fibers using femtosecond laser and phase mask method

[0026] The schematic diagram of the optical path for writing FBG in few-mode fiber by femtosecond laser and phase mask method is as follows figure 2 shown. A femtosecond laser with a center wavelength of 800 nm, a pulse width of 35 fs, a repetition frequency of 1 KHz and a beam diameter of 8 mm is generated by the femtosecond laser 1 . The half-wave plate 2 and the polarizer 3 are sequentially placed in the optical path to adjust the intensity of the femtosecond laser, so that the intensity of the femtosecond laser is 700 μJ. The femtosecond laser is focused by a plano-convex cylindrical lens 4 with a fo...

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Abstract

The invention relates to a method for realizing simultaneous sensing of temperature, strain and refractive index through a single fiber bragg grating (FBG). A localized FBG is written in a few-mode fiber by using femtosecond laser. The FBG transmitted spectrum is provided with multiple bragg resonance peaks and multiple cladding mode resonance peaks. All the bragg resonance peaks have different responses to the temperature and the strain and are not sensitive to the external refractive index. All the cladding mode resonance peaks have different responses to the external refractive index and the strain and are not sensitive to the temperature. The amount of movement of two bragg resonance peaks selected in the FBG transmitted spectrum and the normalized area ( the specific value of the area formed by enclosing of the upper and lower envelop of the cladding mode resonance peaks to the initial area) of the cladding mode resonance peaks are measured so as to realize simultaneous sensing of the temperature, the strain and the refractive index through the single FBG. The beneficial effects of the method are that the method has high sensing sensitivity, the signals are easy to demodulate, the sensing head is easy to manufacture and the mechanical strength is high with no requirement for special packaging.

Description

technical field [0001] The invention relates to a multi-parameter simultaneous sensing method based on a fiber Bragg grating (FBG), which belongs to the technical field of optical fiber sensing, and in particular to a single FBG-based simultaneous sensing method for temperature, strain and refractive index. Background technique [0002] Simultaneous sensing of temperature and strain or temperature and refractive index has a wide range of needs in aerospace, construction, petrochemical, bioengineering, environmental monitoring, and life sciences. FBG has many advantages such as high sensitivity, anti-electromagnetic interference, corrosion resistance, small size, light weight, low insertion loss, easy reuse, and can be embedded in smart materials. It has been used in temperature, pressure, strain, refractive index, bending, vibration and It has been widely used in magnetic field sensing and so on. [0003] However, the characteristic of being sensitive to multiple physical q...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01D21/02G01D5/353
CPCG01D5/35316G01D21/02
Inventor 姜亚军赵建林杨德兴袁元
Owner NORTHWESTERN POLYTECHNICAL UNIV
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