Pulse coding distribution-type fiber Raman and Brillouin scattering sensor

Abstract

The invention discloses a pulse coding distribution-type fiber Raman and Brillouin scattering sensor which comprises a waveform generator, a semiconductor F-P (Fabry-Perot) cavity broadband fiber laser, a semiconductor outer cavity narrow-band pulse fiber laser, a fiber wave separator, a pulse coding photomodulator, an one-way device, an Er-doped fiber amplifier, a bidirectional coupler, a sensing fiber, an integrated wavelength division multiplexer, two photoelectric receiving and amplifying modules, a direct detection system, a narrow-band transmission fiber bragg grating, a circulator, a coherent detection system and an industrial personal computer. The sensor adopts tow laser sources, wherein the semiconductor F-P cavity broadband fiber laser measures temperature by use of a spontaneous fiber Raman scattering intensity ratio; and the other one semiconductor outer cavity narrow-band pulse fiber laser measures strain of frequency shift by use of the spontaneous fiber Brillouin scattering ray. A time sequence codes laser pulse, the spatial resolution is improved by lowering laser pulse width while the transmission photon number is improved, the signal to noise ratio of the systemis improved, and the measurement precision is measured and improved while on-line temperature and strain are realized in space.

Description

technical field [0001] The invention relates to a pulse code distributed optical fiber Raman and Brillouin scattering sensor, belonging to the technical field of optical fiber sensing. Background technique [0002] In the field of distributed optical fiber sensors, there are distributed optical fiber Raman scattering photon temperature sensors at home and abroad to detect the temperature of the scene, and there are distributed optical fiber Brillouin scattering photon sensors abroad to detect the strain and temperature of the scene. Due to the cross effect, they cannot be simultaneously To measure the strain and temperature of the optical fiber, the Newson research team at the University of Southampton proposed to use a narrow-band laser source to measure the temperature using the back spontaneous anti-Stokes Raman scattering of the optical fiber and use the Brillouin scattering effect of the optical fiber to measure the strain. However, due to the The spectral bandwidth of ...

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Problems solved by technology

[0002]In the field of distributed optical fiber sensors, there are distributed optical fiber Raman scattering photon temperature sensors at home and abroad to detect the temperature on site, and there are distributed optical fiber Brillouin scattering photon sensors abroad The sensor detects the strain and temperature of the field. Due to the cross effect, the strain and temperature of the optical fiber cannot be measured at the same time. The Newson research team of the University of Southampton, UK proposed to use a narrow-band laser light source to measure the temperature by using the back spontaneous anti-Stokes Raman scattering of the optical fiber. And use the spontaneous fiber Brillouin scattering effect to measure strain, but because the spectral bandwidth of fiber Brillouin scattering is very narrow, the accuracy of measuring temperature and strain is low (M.N.Allahbabi, Y.T.Cho and T.P.Newson, Simulataneous Distributed Measurements of Temperature and Strain using Spontaneous Raman and Brillouin Scattering, Optics Letters, 2005, 1 June, p.1276-1278)

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