Single-ended structure dynamic measuring Brillouin optical fiber sensing system and sensing method

Abstract

The invention discloses a single-ended structure dynamic measuring Brillouin optical fiber sensing system and a sensing method. A sensing system laser light source outputs two continuous lights through a first coupler, the first continuous light enters the input end of a modulation high-extinction-ratio module, the modulation high-extinction-ratio module is connected to one input end of a second coupler; the second continuous light enters a phase shift modulating module, the phase shift modulating module is connected to the other input end of the second coupler; the second coupler is connected to the port I of an optical circulator, the port II of the optical circulator is connected with a single-ended module by the sensing optical fiber, the port III of the optical circulator is connected with a de-modulating module. By utilizing the single-ended structure, the BOTDA (Brillouin optical time domain analysis) nominal measuring distance is the effective measuring distance, the problems that the double-ended access is required in the actual measurement and the effective sensing distance is a half of the nominal sensing length existing in the prior art are solved; the extinction ratio of electro-optical modulator is improved, the measuring time is shortened, the monitoring functions of dynamic measurement and long-distance dynamic stress are realized.

Description

technical field [0001] The invention relates to optical fiber sensing technology, in particular to a Brillouin optical fiber sensing system and sensing method for dynamic measurement of a single-end structure. Background technique [0002] When the frequency difference of the two beams of light waves transmitted in opposite directions in the fiber is within the range of the inherent Brillouin gain of the fiber, the two beams of light will undergo stimulated Brillouin interaction through the acoustic wave field, and energy transfer will occur between the two beams of light. When the two beams When the frequency difference of light is equal to the inherent Brillouin frequency shift (BFS) of the optical fiber, the amount of energy transfer is the largest. Based on this, the Brillouin frequency shift distribution along the length of the optical fiber can be measured, and the Brillouin optical time domain Brillouin optical time domain analysis (BOTDA) technology is based on the a...

AI Technical Summary

Problems solved by technology

On the other hand, double-ended injection is inconvenient in practical use

At the same time, when the electro-optic modulator is used to modulate the pulsed light, due to the limited extinction ratio of the electro-optic modulator, leaked continuous light will inevitably be generated in the system, and these continuous lights will interfere with the measurement of actual data in the sensing fiber

In order to improve the extinction ratio of the electro-optic modulator and reduce the influence of light leakage in the system, an electro-optic modulator with a high extinction ratio is required, which will cause a sharp increase in the cost of system instruments

In addition, the traditional BOTDA needs to sweep the frequency difference between the pump light and the probe light to obtain the Brillouin frequency shift. The frequency sweep is very time-consuming, so the traditional sweep-based BOTDA system is not suitable for the measurement of dynamic events.

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