Phase-sensitive optical time domain reflection system based on self-mixing technology

Abstract

The invention discloses a phase-sensitive optical time domain reflection system based on self-mixing technology, which is composed of an optical path detection part and a circuit demodulation part. The optical path is composed of a narrow linewidth laser (1), an optical coupler (2), an acoustic-optical degree modulator (3), a pulse function generator (4), a circulator (5), an optical fiber (6) and a polarization controller (7). The circuit is composed of a bandpass filter (10), a low-noise amplifier (11), a power divider (12), a frequency mixer (13) and a low-pass filter (14). As the simple self-mixing structure is adopted, demodulation on modulated signals can be realized, and inconvenient demodulation caused by frequency drift of a local optical signal can be eliminated. In the phase-sensitive optical time domain reflection technology system by adopting a coherent detection method, frequency drift of local light is a problem which needs to be considered. Influences brought by frequency drift of the local light can be well eliminated. The device is stable in work, and the vibration position and the vibration frequency can be accurately measured in multiple times of measurement.

Description

Technical field [0001] The present invention relates to a distributed optical fiber sensing technology-demodulation technology in phase-sensitive optical time-domain reflection technology. Specifically, it is applied to a phase-sensitive optical time-domain reflection system to form a self-mixing-based Phase-sensitive optical time-domain reflection system based on frequency technology. Background technique [0002] In recent years, with the rapid development of oil and gas pipelines, high-speed railways, and large buildings, distributed optical fiber sensing technology has attracted more and more attention from all walks of life. However, due to its many advantages, distributed optical fiber sensing technology has become The key technology for external information perception in long-distance and harsh environments. The phase-sensitive optical time domain reflection technology is just one of the members of the distributed optical fiber sensing technology family. Its main function...

AI Technical Summary

Problems solved by technology

However, the electric signal of this technology needs to be demodulated again. At present, there are mainly two types of demodulation technology applied to this technology: A. Coherent demodulation; B. Orthogonal demodulation; both demodulation technologies need to generate a Local signal, and this local signal cannot follow the frequency drift of the broadband signal caused by the frequency drift of the local optical signal, so the signal cannot be demodulated well during demodulation

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