Method for realizing simultaneous sensing of temperature, strain and refractive index through single fiber bragg grating

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...

AI Technical Summary

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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