Distributed fiber Raman temperature measuring device and method based on ASE noise

Abstract

The invention relates to a distributed fiber sensing system, and specifically relates to a distributed fiber Raman temperature measuring device and method based on ASE noise. The distributed fiber Raman temperature measuring device and method based on ASE noise solve the contradiction between the spatial resolution and the measurement distance existing in a pulsed-light-based distributed fiber Raman temperature measuring system, and overcome the problem that in a distributed fiber Raman temperature measuring system based on chaotic laser, the chaotic laser is taken as a sensing signal, thus reducing the system performance. The system includes an ASE noise light source, a first tunable optical filter, a first 1*2 fiber coupler, a photoelectric detector, an optical circulator, a second1*2 fiber coupler, a second tunable optical filter, a first avalanche photoelectric detector, a first low-noise amplifier, a third tunable optical filter, a second avalanche photoelectric detector, a secondlow-noise amplifier, a data collection card, a computer and a sensing fiber.

Description

technical field [0001] The invention relates to a distributed optical fiber sensing system, in particular to a distributed optical fiber Raman temperature measuring device and method based on ASE noise. Background technique [0002] There are more and more large buildings such as submarine tunnels, bridge tunnels, skyscrapers, giant factories, etc. Once a fire or other accident occurs in these places, it will not only cause major economic losses to the country, but also cause huge casualties. For example: at about 11 o'clock on March 15, 2004, a huge fire broke out in Zhongbai Commercial Building, Jilin City, Jilin Province. The fire eventually killed 54 people, injured 70 others, and caused a direct economic loss of 4.26 million yuan; A fire broke out in the Jintian Commercial Building in Lishi District, Lvliang City, killing 8 people. At 14:00 on November 15, 2010, a high-rise apartment building on Jiaozhou Road, Yuyao Road, Shanghai caught fire. The fire eventually killed...

AI Technical Summary

Problems solved by technology

For pulsed lasers, on the one hand, the response accuracy of the receiving end is high, and signal capture is difficult; on the other hand, the system monitoring distance is proportional to the pulse width, and the spatial resolution is inversely proportional to the pulse width. If the pulse width is narrowed in order to improve the spatial resolution It will reduce the monitoring distance, which will lead to the contradiction between the monitoring distance and the spatial resolution

At present, the distributed optical fiber Raman sensing system based on pulsed laser has a spatial resolution of more than 1 meter, which is difficult to meet the needs of practical applications.

In order to solve the contradiction between spatial resolution and monitoring distance, a distributed optical fiber Raman temperature measurement system based on chaotic laser was proposed [Chinese patent: ZL 201110227239.9]. However, chaotic laser is usually provided by optical feedback or optical injection, or It is generated by optical feedback combined with optical injection to disturb the semiconductor laser, which will contain periodic signals introduced by optical injection and optical feedback, which will seriously affect the spatial resolution of the Raman temperature measurement system

At the same time, to generate a chaotic laser signal with adjustable spectrum and controllable coherence length, multiple parameters need to be adjusted, and the light source structure and implementation process are complex and time-consuming

[0004] Therefore, it is necessary to develop a new Raman temperature measurement system, which can not only solve the contradiction between the spatial resolution and the monitoring distance of the traditional Raman temperature measurement system, but also overcome the problem caused by the chaotic laser as the sensing signal. itself brings about the problem of system performance degradation

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