A Brillouin-amplified optical time domain reflectometer type optical fiber sensing system

Abstract

The invention discloses an optical time domain reflectometer type optical fiber sensing system based on Brillouin amplification and belongs to the technical field of optical fibers. The optical time domain reflectometer type optical fiber sensing system comprises a first narrow linewidth light source, a frequency shifting device, a narrow linewidth filter, a scrambler, a long-distance sensing optical fiber, a circulator, an acoustic optical modulator, a first optical fiber coupler and a second narrow linewidth light source. Continuous light generated by the second narrow linewidth light source is divided into two paths through the first optical fiber coupler, wherein in one path, signal light is modulated through the acoustic optical modulator to generate high-extinction-ratio pulse signal light and is connected to the long-distance sensing optical fiber through the circulator; frequency shift is conducted on the first narrow linewidth light source through a frequency shifter, so that the frequency difference between the signal light frequency and the pump light frequency is the Brillouin frequency shifting value of the sensing optical fiber, the first narrow linewidth light source is connected to the scrambler through the narrow linewidth filter for scrambling, and the pump light is prevented from being generated and connected with the long-distance sensing optical fiber. Distributed amplification is conducted on the signal light and the signal light intensity and the signal to noise ratio of the receiving end in the long-distance sensing optical fiber are improved through the pump light with relatively low power.

Description

technical field [0001] An optical time domain reflectometer type optical fiber sensing system based on Brillouin amplification is used for amplifying signal light intensity in the optical fiber sensing system, prolonging the sensing distance and improving sensitivity, and relates to the field of optical fiber technology. Background technique [0002] The types of distributed optical fiber sensing systems include: phase-sensitive optical time-domain reflectometer (φ-OTDR), polarization-sensitive optical time-domain reflectometer (POTDR), etc. [0003] The phase-sensitive optical time domain reflectometer demodulates the amplitude and phase of the electric field of the Rayleigh signal scattered along the optical fiber link in real time, and detects the disturbance at one or more points on the sensing fiber by analyzing the demodulated amplitude and phase. It is an extremely valuable distributed optical fiber sensing technology, which can perform distributed, multi-point and re...

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Problems solved by technology

[0007] 1. The Raman pump power often needs to reach more than several watts, and the performance requirements of the pump laser are relatively high;

[0008] 2. If the Raman pump power reaches several watts or more, it is easy to damage the optical fiber connector of the system, thus making the system completely invalid;

[0009] 3. High-power Raman pump light is injected into the sensing fiber for a long time, and it is easy to cause irreversible changes in the physical properties of the sensing fiber, which affects system performance.

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