Distributed optical fiber sensing device based on brillouin scattering

Abstract

The invention discloses a distributed optical fiber sensing device based on Brillouin scattering, comprising a first detection light source, a second detection light source, a first pumping light source, a second pumping light source, a first optical switch module, a second An optical switch module, a first coupler, a second coupler, a frequency measurement module, a detection light output and signal processing module, a pump light output module and a sensing optical fiber module. The first detection light source and the first pump light source or the second detection light source and the second pump light source are selected as the light source of the Brillouin optical time domain analyzer through the first optical switch module and the second optical switch module, thereby realizing a single type The device for simultaneously measuring the strain and temperature of the sensing fiber solves the problem of temperature and strain cross-sensitivity effects in Brillouin distributed fiber sensing. The device has a simple structure and low cost, and has no special requirements for the specifications of the sensing fiber , with a wide range of applications, especially suitable for distributed on-line monitoring applications of existing projects.

Description

technical field [0001] The invention relates to a distributed optical fiber sensing device based on Brillouin scattering, in particular to a distributed optical fiber sensing device for simultaneously measuring temperature and strain. Background technique [0002] Distributed optical fiber sensors have important applications in the safety monitoring of important infrastructure such as electric power, bridges, dams, and petrochemicals. Compared with the distributed optical fiber sensor based on Raman scattering, the distributed optical fiber sensor based on Brillouin scattering has a longer measurement distance, higher measurement accuracy, and realizes temperature and stress measurement. focus on. [0003] There are two types of distributed optical fiber sensors based on Brillouin scattering: Brillouin Optical Time Domain Reflection (BOTDR) and Brillouin Optical Time Domain Analysis (BOTDA). Among them, BOTDR is a single-ended measurement with a simple structure, but it de...

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Problems solved by technology

For example, Bao X et al. used special fibers such as polarization-maintaining fibers, photonic crystal fibers, and large effective area fibers as measuring fibers, and used multiple Brillouin frequency shift peaks to separate temperature and strain values ​​("Simultaneous strain and temperature measurements with polarization -maintaining fibers and their error analysis by use of a distributed Brillouin loss system, "Optics letters, 29(12):1342-1344, 2004), but due to the high price and poor availability of special optical fibers, the cost of long-distance measurement is too high

As another example, the invention patent with application number 201010229960.7 discloses a measurement optical fiber with at least two Brillouin frequency shift temperature coefficients and stress coefficients that are arranged in parallel, and realizes the Brillouin frequency shift of the two optical fibers by means of an optical switch. The measurement of the change in deep frequency shift solves the cross-sensitive effect of Brillouin frequency shift on temperature and strain through simultaneous equations, but two types of single-mode optical fibers need to be laid in advance

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