Phase-sensitive optical time domain reflection system based on dual-wavelength frequency diversity

Abstract

The invention belongs to the technical field of distributed optical fiber sensing, and discloses a phase-sensitive optical time domain reflection system based on dual-wavelength frequency diversity. A coherent detection phase-sensitive optical time domain reflection system with a detection light wavelength of 1550nm and an auxiliary interference structure with a detection light wavelength of 1310nm are combined by using a wavelength division multiplexing technology; an external vibration signal is quickly sensed by means of the auxiliary interference structure, so that switching between a single-frequency detection state and a multi-frequency detection state is realized by utilizing computer control, and waste of computing resources caused by multi-frequency detection when no external vibration signal exists is avoided. Besides, in a multi-frequency detection state, a random number generator is utilized to generate a random signal to drive and control a phase modulator, so that random change of the intensity of three frequency components in multi-frequency detection laser is realized, the non-correlation degree among the frequency components in multi-frequency Rayleigh back scattering light is enhanced, and the frequency diversity efficiency is improved. Therefore, the real-time performance of the system can be improved while interference fading suppression is realized.

Description

technical field [0001] The invention belongs to the technical field of distributed optical fiber sensing, in particular to a dual-wavelength frequency diversity phase-sensitive optical time-domain reflection system. Background technique [0002] In recent years, fiber optic vibration sensing technology has attracted the attention of many researchers due to its advantages of corrosion resistance, good insulation, anti-electromagnetic interference, and wide measurement range. As a typical optical fiber vibration sensing system, the phase-sensitive optical time-domain reflectometry system has shown great application potential in the fields of structural health monitoring, perimeter security, and oil and gas pipeline monitoring due to its fast response speed and high sensitivity. [0003] Phase-sensitive optical time-domain reflectometry systems generate probe light from a narrow-linewidth laser that continuously generates Rayleigh backscattered light as it propagates through an...

AI Technical Summary

Problems solved by technology

Compared with the single-frequency detection state, the multi-frequency detection state needs to perform operations such as filtering, aggregation, and phase demodulation on the signals of multiple frequency components, resulting in a multiplied signal processing time.

In addition, since the vibration signal does not always exist, multi-frequency detection when there is no external vibration signal will waste a lot of computing resources and seriously affect the real-time performance of the system response

At the same time, the intensity of multiple frequency components in traditional frequency diversity technology is usually fixed, resulting in a certain correlation between Rayleigh backscattered light of different frequencies, which affects the frequency diversity efficiency.

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