Ultra long distance distributed optical fiber vibration sensing device

Abstract

The invention relates to the technical field of optical fiber sensing and particularly relates to an ultra long distance distributed optical fiber vibration sensing device. The device is characterized in that the device comprises a light source, an acousto-optic modulator, a 1*2 optical splitter, an erbium-doped fiber amplifier, 1*2 couplers, circulators, wavelength division multiplexers, photoelectric detectors, a signal processor, a data acquisition card, sensing fibers and an industrial control computer, the light source is connected with the 1*2 optical splitter, one output of the optical splitter is connected with a first 1*2 coupler, two outputs of the first 1*2 coupler are respectively connected with the output ends of a second 1*2 coupler and a third 1*2 coupler, another output of the optical splitter is connected with the fiber input end of the acousto-optic modulator, and the signal end of the acousto-optic modulator is connected with a synchronous pulse output channel of the data acquisition card, and the fiber output end of the acousto-optic modulator is connected with the erbium-doped fiber amplifier. According to the ultra long distance distributed optical fiber vibration sensing device, under the premise of not increasing the cost of the original main components, the sensing distance is increased by one time, and the ultra long distance vibration monitoring is realized.

Description

technical field [0001] The present invention relates to the technical field of optical fiber sensing, in particular to a phase-sensitive carrier modulation technology and coherent monitoring technology, which can effectively improve the signal-to-noise ratio of the system, greatly increase the sensing distance, and further realize an optical cable longer than 60 kilometers An ultra-long-distance distributed optical fiber vibration sensing device for monitoring vibration signals along the line and judging intrusion. Background technique [0002] In recent years, the issue of perimeter security has attracted global attention. As soon as the application products of distributed optical fiber sensing technology in the perimeter defense system appear, they have been extensively and in-depth researched at home and abroad, and in more than ten years developed rapidly. The implementation methods of distributed optical fiber vibration sensors are divided into two categories, namely ...

AI Technical Summary

Problems solved by technology

However, due to the characteristics of ordinary single-mode optical fibers, the polarization state will change during long-distance transmission. Because of the degradation of the polarization state, the quality of the interference signal output will be affected. In severe cases, the signal will not meet the interference conditions, resulting in distributed fiber vibration. The positioning accuracy of the sensor deteriorates and the problem of inability to monitor

Polarization-maintaining fiber can be used to solve this phenomenon, but because the price of polarization-maintaining fiber and its supporting components is very expensive, it cannot be used in practical applications

At present, many research institutions are also conducting research on this kind of phenomenon. The anti-polarization ability of the system is improved through the polarization controller and related modulation technology. The system index has been improved to a certain extent, and the system cost has also doubled.

And compared with the distributed optical fiber vibration sensing technology based on OTDR technology, its positioning accuracy is still low, and there is a problem of high false alarm rate

[0004] The existing distributed optical fiber vibration sensor based on OTDR technology can only realize the monitoring of more than ten kilometers of optical cables along the line due to the detection of backscattered signals, weak signal strength, and short detection sensing distance.

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