Optical fiber vibration sensor based on delayed phase-modulated chirped pulse pairs

Abstract

The invention relates to an optical fiber vibration sensor based on delay phase-modulated chirped pulse pairs. The sensor comprises a narrow linewidth laser, a first optical fiber coupler, an electro-optical modulator, an acousto-optic modulator, an optical amplifier, a second optical fiber coupler, a delay optical fiber, an optical fiber expansion device, a first Faraday rotator mirror, a secondFaraday rotator mirror, an annular device, a to-be-measured optical fiber, a third optical fiber coupler, a first polarization controller, a fourth optical fiber coupler, a second polarization controller, a fifth optical fiber coupler, a sixth optical fiber coupler, a first double-balance detector, a second double-balance detector, a first analog-to-digital converter, a second analog-to-digital converter, a first digital signal processing unit, a second digital signal processing unit and an arbitrary waveform generator. With the optical fiber vibration sensor adopted, the contradiction betweenspatial resolution and sensing distances in a traditional sensing system based on a time-domain reflectometer can be eradicated; the problem of interference attenuation in an interference sensing system can be solved; and indexes such as a long sensing distance, high spatial resolution and a high signal-to-noise ratio can be achieved simultaneously.

Description

technical field [0001] The invention relates to the technical field of distributed optical fiber sensing, in particular to a high-performance optical fiber vibration sensor based on delayed phase modulation chirped pulse pairs. Background technique [0002] Optical fiber sensor has strong anti-electromagnetic interference ability, non-invasiveness, easy to realize long-distance monitoring of the measured signal, corrosion resistance, explosion-proof, flexible optical path, easy to connect with optical fiber system and other advantages. In recent years, it has been widely used in natural gas and oil pipeline safety monitoring, bridge crack monitoring, gas concentration detection, border security and other fields. [0003] Phase-sensitive optical time domain reflectometer (Φ-OTDR) is a new type of distributed optical acoustic sensing technology (DAS), which can realize distributed dynamic detection by using the backward Rayleigh scattering in optical fiber. The main performan...

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Problems solved by technology

[0006] The purpose of the present invention is to overcome the mutual restriction and contradictory relationship between the sensitivity and spatial resolution of the existing optical fiber sensing system and the sensing distance, solve the interference fading problem existing in the system at the same time, and improve the Φ-OTDR A number of key indicators to build a high-performance Φ-OTDR sensing system

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