Distributed stimulated Brillouin temperature strain sensing system based on double-sideband modulation

Abstract

The invention provides a distributed stimulated Brillouin temperature strain sensing system based on double-sideband modulation, which includes a narrow linewidth light source, a power divider, a microwave source, a pulse signal emitter, an optical receiver, an optical amplifier, an electrooptical modulator and a sensing optical fiber, wherein a pulse optical signal and a continuous signal that is modulated by double-sideband are input into the two ends of the sensing optical fiber respectively; the pulse optical signal serves as a pumping optical signal; the double-sideband continuous optical signal serves as a detecting optical signal; the pumping optical and detecting optical signals encounter to produce the stimulated Brillouin; and the continuous light carries the temperature or strain information of the points distributed along the sensing optical fiber. The double-sideband technology can effectively controls the Brillouin consumption of the pumping pulse during transmission, and greatly reduces the system error in measurement. The distributed stimulated Brillouin temperature strain sensing system is applicable to the fields as transmission cable and oil-gas pipeline monitoring and fire control, and is particularly applicable to sensing of long distance more than 50km.

Description

technical field [0001] The invention belongs to the field of optical fiber technology, and relates to an optical fiber temperature strain sensing system, in particular to a distributed stimulated Brillouin temperature strain sensing method and structure based on double sideband modulation. Background technique [0002] The distributed optical fiber temperature and stress sensing system based on the stimulated Brillouin effect has the ability to simultaneously obtain the temperature or stress change information of the measured area with time and space, and is suitable for long-distance distributed detection. With its intrinsic explosion-proof, passive and long-distance characteristics, this type of sensor is applied in the fields of oil and gas pipelines, electric power and fire protection, and solves the technical problems that have existed in many industries for many years. It is an important technology in the field of fire protection to monitor and provide precise position...

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Problems solved by technology

[0004] figure 1 In the prior art shown in , the light source of the sensing system is composed of two lasers, and an additional frequency locker 103 is required to ensure the frequency difference between the two is stable, and the system is relatively complicated

Moreover, when the pump pulse is transmitted in the sensing fiber, it will have Brillouin interaction with the probe light, and the power will continue to decrease. With the accumulation of a certain length, the power will have a significant gap with the theoretical value, resulting in systematic measurement errors. Therefore, the sensing distance is greatly limited

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