Brillouin distributed optical fiber sensor and method of reducing gain spectrum line width

Abstract

The invention discloses a Brillouin distributed optical fiber sensor and a method of reducing a gain spectrum line width. Continuous light generated by a light generation unit passes through a first modulation amplification unit to obtain phase modulation signals; the phase modulation signals pass through a second modulation amplification unit to generate pumping light pulse signals; the pumping light pulse signals are injected to the beginning end of a sensing optical fiber through a circulator; continuous light of the other side path passes through a third modulation amplification unit to obtain bilateral band signals suppressing carriers; and light signals are filtered through a filter to obtain Stokes light or anti-Stokes light, and then the light signals are converted to electric signals through a photodetector. On the premise of not worsening the system spatial resolution, a narrower Brillouin gain spectrum, a higher temperature resolution and a longer sensing distance can be realized.

Description

technical field [0001] The invention relates to the field of distributed optical fiber sensors, in particular to a method for reducing the line width of the gain spectrum of a distributed excited Brillouin temperature or strain sensor. Background technique [0002] Long-distance, distributed temperature or stress detection, temperature or load monitoring on smart grid lines, fire prevention warnings in forests, roads, railways, tunnels, etc., building structure health monitoring, etc., important protection areas, communication or oil pipelines, traffic lines And there are major application requirements in areas such as important border invasion warnings and oil and gas pipeline leakage, which have received long-term and in-depth research in academia and industry. At present, the technologies that can realize long-distance distributed detection are mainly divided into "point" quasi-distributed sensors and optical fiber-based distributed sensors. [0003] Traditional "point" ...

AI Technical Summary

Problems solved by technology

[0007] Although the Brillouin gain of the traditional DPP-BOTDA system can maintain the limit Brillouin linewidth (~30 MHz) and the ultimate spatial resolution, its Brillouin gain spectrum linewidth cannot be further compressed, and due to the differential pulse The weaker signal in the non-hot spot area leads to a weaker signal-to-noise ratio, which increases the Brillouin frequency shift measurement error in the non-hot spot area.

This makes the performance of distributed sensors based on the stimulated Brillouin effect stagnate, and the system indicators cannot be further greatly improved, which is also the root cause of the large-scale commercialization of this technology.

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