BFS measurement device, method and optical fiber distributed sensing system

Abstract

The embodiment of the invention provides a BFS measuring device and method and a fiber distributed sensing system. First branch detection light is modulated into a double-sideband 2FSK signal for suppressing a carrier; and a Brillouin intrinsic spectrum misalignment phenomenon corresponding to the side band of the first branch detection light is weakened or eliminated during the frequency sweepingprocess, so that first pulse optical distortion is compensated and thus the incident power of the first branch detection light and the sensing distance of the optical fiber are improved and the measured first BFS of the sensing fiber becomes accurate. Moreover, the measuring device can still work accurately under the circumstances that the fiber distance is too long and second BFS differences between fibers are too large.

Description

technical field [0001] The invention relates to the technical field of sensing systems, in particular to a BFS measuring device, method and optical fiber distributed sensing system. Background technique [0002] Optical fiber distributed sensing system is a sensing system that uses light waves as sensing signals and optical fibers as transmission media. It can perceive and detect the continuous distribution information of the external measured physical quantity with time and space. Among many distributed sensing systems, BOTDA (Brillouin optical time domain analysis, Brillouin optical time domain analysis) technology relies on its physical characteristics of simultaneously measuring temperature and stress information, as well as its core advantages of achieving longer measurement distances , has been one of the research hotspots in the field of optical fiber sensing. [0003] In the BOTDA system, one end of the sensing fiber is incident with a pump pulse, and the other end...

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Problems solved by technology

However, in the frequency domain, during the sweeping process, the Brillouin eigenspectrum corresponding to the sidebands of the probe light will be dislocated, which will distort the spectrum shape of the pulsed light after the action, and limit the incident power of the probe light and the transmission of the fiber. Sensitive distance, resulting in BFS system error; when the fiber length is long (each section is greater than 25km) and the BFS of each section of fiber differs greatly, the existing technology degenerates into a common single-sideband BOTDA sensor except for the last section of fiber at the end , the system is affected by non-local effects, which will also limit the incident power of the probe light and the sensing distance of the optical fiber, and further cause the BFS system error

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