Brillouin optical time domain reflectometer modulated by physical random number

Abstract

The invention belongs to the technical field of distributed optical fiber sensing. The invention provides a Brillouin optical time domain reflector modulated by the physical random number, aiming at the compromise between the spatial resolution, the signal-to-noise ratio, and the measurement precision of the Brillouin optical time domain reflector in the prior art. The Brillouin optical time domain reflector comprises a first DFB laser emitting module, a second DFB laser emitting module, a first optical fiber coupler, a pulse optical amplifier, a second optical fiber coupler, a polarization controller, a gain switch modulator, a physical random number generating module, a DWDM dense type wavelength division multiplexer, a sensing optical fiber, an optical fiber circulator, a continuous optical amplifier, an optical filter, a third optical fiber coupler, a scrambler, a photodetector, a mixer, a microwave adjustable frequency source, an electric amplifier, an electric filter, an A / D conversion module, and a host computer. The invention can monitor the strain magnitude and location of the sensing optical fiber along the line in real time with high precision under the premise of ensuring spatial resolution.

Description

technical field [0001] The invention relates to a Brillouin optical time domain reflectometer and belongs to the technical field of distributed optical fiber sensing. More specifically, the invention relates to a Brillouin optical time domain reflectometer modulated by a physical random number. Background technique [0002] In recent years, distributed optical fiber sensing detection technology has developed rapidly. Compared with quasi-distributed optical fiber sensing, distributed optical fiber sensing technology combines sensing and transmission into one, and can measure all positions along the entire optical fiber. Environmental change information has the characteristics of anti-electromagnetic interference, corrosion resistance, long-distance transmission, simple structure, and large dynamic measurement range, so it is widely used in structural health monitoring of large buildings, highways, dams, and bridges, as well as underground pipeline networks, oil and gas Safety...

AI Technical Summary

Problems solved by technology

In order to solve the problem of improving the signal-to-noise ratio of the system under the condition that the measurement time and spatial resolution remain unchanged, some of the existing schemes use the cumulative average time method, some use the method of increasing the pulse width, and some Coding methods such as Golay are used, but these methods have their own defects: the use of the cumulative average time method will greatly prolong the measurement time of the system and affect the real-time performance of the system; if the pulse width is increased, the spatial resolution will inevitably be reduced, affecting The accuracy of the system for small events; if Golay and other encoding methods are used, it is easy to cause inter-symbol interference during decoding of the four sets of encoded pulses, which affects the demodulation accuracy of the system

None of the existing methods can solve the compromise problem of system spatial resolution, signal-to-noise ratio and measurement accuracy. Therefore, it is necessary to propose a Brillouin optical time-domain reflectometer with high signal-to-noise ratio

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