Distributed strain and temperature optical fiber sensor based on brillouin scattering

Abstract

The invention discloses a distributed strain and temperature optical fiber sensor based on brillouin scattering. The sensor comprises a light source, an electro-optical modulator, a pulse signal source, a first erbium-doped optical fiber amplifier, a second erbium-doped optical fiber amplifier, a circulator, a first optical coupler, a second optical coupler, double balance detectors, a signal processing system and a sensing optical fiber. The sensing optical fiber comprises a long period optical fiber grating and is an all-solid photonic crystal band gap optical fiber. Output light of the light source is divided into two paths, wherein one path of the output light is modulated to be detection pulse light by means of the electro-optical modulator, is amplified through the erbium-doped optical fiber amplifiers and is input into the sensing optical fiber through the circulator. The sensor can simultaneously obtain temperature and strain with high resolution through a single measurement, and can well solve the problem of cross sensitivity existing in measurement of a brillouin sensor.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing, in particular to a distributed strain and temperature optical fiber sensor based on Brillouin scattering. Background technique [0002] Brillouin scattering is a light scattering process caused by the interaction between light waves and sound waves propagating in optical fibers. There is a certain frequency difference between Brillouin scattering and incident light, and the frequency difference has good linearity with temperature and strain. relationship, while its power is proportional to temperature. As a sensing medium, optical fiber has the advantages of small size, light weight, anti-electromagnetic interference, and easy networking. Distributed sensing of temperature and strain in the environment can be realized by measuring the Brillouin spectrum in the optical fiber, which has received more and more attention in the sensing of buildings such as bridges, tunnels, reservoirs,...

AI Technical Summary

Problems solved by technology

For photonic crystal fibers based on air holes, the air holes suppress the acousto-optic effect of backscattering to a certain extent, so the Brillouin peak generated by the optical field distributed in the glass core In addition to being strong, the power of other Brillouin peaks is very weak, and the signal-to-noise ratio of the measured Brillouin scattering signal is poor, which reduces the resolution of the system

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