Very long range pulse coding distribution type Fiber Raman and Brillouin photon sensor

Abstract

The invention discloses a very long range pulse coding distribution type Fiber Raman and Brillouin photon sensor which is a sensor for measuring temperature and strain and is manufactured by use of the pulse coding principle, the fiber stimulated Raman scattering effect, the spontaneous Raman scattering temperature effect, the spontaneous Brillouin scattering strain effect and the optical time domain reflection principle. Amplified pulse coding reverse anti-Stokes and Stokes Raman scattered lights are directly output into a detection system to be decoded and demodulated by two photoelectric receiving modules to measure the intensity ratio of the lights so as to obtain the temperature information of each section of a fiber. The amplified pulse coding reverse fiber Brillouin scattering light and the beat frequency of the local light of an external-cavity narrow-band fiber laser are subjected to coherent detection, and the strain information of each section of the fiber is obtained by decoding measurement frequency shift. The sensor adopts a time sequence to code laser pulse to effectively increase the photon number of an incident sensing fiber and improve the signal to noise ratio. According to the sensor, the measurement length is increased, and the measurement precision and the spatial resolution are improved.

Description

technical field [0001] The invention relates to an ultra-long-distance pulse coding distributed optical fiber Raman and Brillouin photon sensor integrated with an optical fiber Raman amplifier, belonging to the technical field of optical fiber sensors. 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 site, and there are distributed optical fiber Brillouin scattering photon sensors abroad to detect the strain and temperature of the site. Due to the cross effect, they cannot be measured at the same time. The strain and temperature of the optical fiber, the Newson research team of the University of Southampton in the United Kingdom 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 spontaneous fiber Brillouin sc...

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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 of the site, and foreign countries have distributed optical fiber Brillouin scattering photon sensors To detect 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. Spontaneous fiber Brillouin scattering effect to measure strain, but due to the narrow spectral bandwidth of fiber Brillouin scattering, 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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