High-precision fiber bragg grating low-frequency strain sensing demodulation system

Abstract

The invention discloses a high-precision fiber bragg grating low-frequency strain sensing demodulation system which comprises a narrow linewidth laser, an electro-optic / acoustic optical modulator, a radio-frequency signal generator, a narrow linewidth optical fiber filter, a coupler, a circulator, a first fiber bragg grating sensor, a second fiber bragg grating sensor, a photoelectric detector and a strain demodulation module. The narrow linewidth laser provides narrow linewidth laser, the electro-optic / acoustic optical modulator modulates the narrow linewidth laser, the radio-frequency signal generator generates a chirp signal, the narrow linewidth optical fiber filter filters the modulated laser, and the coupler divides the obtained single-side-band laser capable of being tuned within the predetermined bandwidth into two paths of light sources. The circulator transmits the light reflected by the first fiber bragg grating sensor and the second fiber bragg grating sensor to the detector, the first fiber bragg grating sensor and the second fiber bragg grating sensor respectively receive outside strain and temperature signals, the photoelectric detector performs photovoltaic conversion on the light reflected by the first fiber bragg grating sensor and the second fiber bragg grating sensor, and the strain demodulation module obtains wavelength difference between the first fiber bragg grating sensor and the second fiber bragg grating sensor according to digital signals and obtains strain values of the fiber bragg grating strain sensors.

Description

technical field [0001] The invention relates to the field of optical fiber technology, in particular to a high-precision optical fiber grating low-frequency strain sensing demodulation system based on laser linear sweep frequency modulation technology. Background technique [0002] At present, Fiber Bragg Grating (FBG) sensors are widely used in various industries. Fiber Bragg grating sensors have many advantages such as small size, fast response speed, wide range of linear response, and easy reuse. However, the strain measurement accuracy of the current commercial fiber grating demodulation equipment is only 1 με, which is difficult to meet the requirements of high-precision deformation measurement fields (such as Crustal deformation monitoring) strain measurement requirements. [0003] At present, people have proposed many methods to improve the strain measurement accuracy of FBG, such as using phase-shifted fiber Bragg gratings and fiber Bragg grating-Pertin interferomet...

AI Technical Summary

Problems solved by technology

[0006] In view of this, the main purpose of the present invention is to provide a high-precision fiber grating low-frequency strain sensing demodulation system based on laser linear frequency sweep modulation technology, which adopts laser linear frequency sweep modulation technology and optical filtering technology to achieve high precision and large dynamic range of strain measurement, and focus on solving the problem that expensive tunable lasers need to be used in fiber grating sensing systems based on tunable lasers, and the poor scanning linearity of tunable lasers leads to limited strain demodulation accuracy and small dynamic range.

Images