Optical fiber detection method and system

Abstract

The embodiment of the invention provides an optical fiber detection method and system. The optical fiber detection system comprises a laser, a sensing optical fiber, a first circulator, a second circulator and a collector, wherein the laser sends a sensing pulse and a pumping pulse to the first circulator, and the sending time of the sensing pulse is earlier than the sending time of the pumping pulse; the first circulator transmits the sensing pulse and the pumping pulse through the sensing optical fiber; after receiving the sensing pulse, the second circulator sends the sensing pulse to the first circulator through the sensing optical fiber, the sensing pulse and the pumping pulse are subjected to stimulated Brillouin scattering in the sensing optical fiber to obtain the sensing pulse carrying the Brillouin scattering information; after receiving the sensing pulse carrying the Brillouin scattering information, the first circulator sends the sensing pulse carrying the Brillouin scattering information to the collector; and after receiving the sensing pulse carrying the Brillouin scattering information, the collector stores the Brillouin scattering information. By applying the technical scheme provided by the embodiment of the invention, optical fibers can be saved, and single-optical fiber long-distance detection is realized.

Description

technical field [0001] The invention relates to the technical field of optical fiber sensing, in particular to an optical fiber detection method and system. Background technique [0002] Distributed optical fiber sensors use optical fiber as the transmission medium, and have the advantages of small size, light weight, easy bending, low loss, anti-electromagnetic interference, and good anti-radiation performance. In the future, smart grids, oilfield pipeline safety monitoring, bridges, and spacecraft wings There are a wide range of application requirements in important fields such as key building structure monitoring. Among them, the Brillouin scattering information obtained by the distributed sensor based on Brillouin scattering includes information such as Brillouin gain and Brillouin frequency shift, which have a linear relationship with temperature and stress changes, so that temperature and stress information can be measured. [0003] At present, compared with the Brill...

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Problems solved by technology

Although the loop technology in the long-distance BOTDA sensor effectively overcomes the problem of out-of-synchronization of laser frequencies at both ends, the improved BOTDA system must use a guide fiber to guide the sensing pulse to the end of the sensing fiber, so that the sensing pulse The SBS effect occurs with the pump pulse in the sensing fiber, and the sensing fiber only accounts for half of the length of the entire fiber (sensing fiber + guiding fiber), which wastes half of the fiber and increases the cost of sensing

[0004] In the self-coherent detection Rayleigh Brillouin time-domain analysis technology, the SBS interaction with the pump pulse is the sensing pulse obtained after the back Rayleigh scattering of continuous light, and the sensing pulse obtained after the continuous Rayleigh scattering of continuous light The pulse power is very low, which limits the sensing distance, and the signal-to-noise ratio of the sensing pulse carrying SBS information obtained after SBS action is low

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