Brillouin time-domain analysis system based on Brillouin laser and automatic heterodyne detection

Abstract

The invention discloses a Brillouin time-domain analysis system based on a Brillouin laser and automatic heterodyne detection and belongs to the technical field of optical fiber sensors. The Brillouin time-domain analysis system comprises a laser, an isolator, a coupler, a first Er-doped fiber amplifier, the Brillouin laser, a signal generator, a phase modulator, sensing optical fiber, a circulator, a second Er-doped fiber amplifier, a pulse generator, a scrambler, a photovoltaic conversion module, and a digital signal processing module. The Brillouin time-domain analysis system is characterized in that the Brillouin laser is used for realizing broadband frequency shift for incoming laser, the phase modulator is used for modulating laser after frequency downward shift so as to generate double-sideband signals, the signals and pulse pump light generated by the pulse generator generate stimulated Brillouin scattering effect in the sensing optical fiber, and optical signals after action conducts automatic heterodyne detection through the photovoltaic conversion module. The Brillouin time-domain analysis system is weakened in phase noise, improves the signal to noise ratio of detection signal, ensures the temperature / strain measurement accuracy of a whole section of the sensing optical fiber, and is made to be more compact.

Description

technical field [0001] The invention relates to an optical fiber Brillouin time domain analysis system and belongs to the technical field of optical fiber sensors. Background technique [0002] The distributed optical fiber sensing technology based on the Brillouin scattering effect is a hot sensing technology researched in recent years. It can sense the spatial distribution and time-varying information of temperature and strain on the entire optical fiber sensing link. It has important application prospects in the health and safety monitoring of major structures such as bridges and dams. Among the Brillouin distributed fiber optic sensors, the Brillouin time domain analyzer uses the stimulated Brillouin scattering effect, which enhances the detection signal and has a longer sensing distance. [0003] At present, it is a difficult technology to improve the signal-to-noise ratio of the detection signal of the Brillouin time-domain analysis system, and the detection methods c...

AI Technical Summary

Problems solved by technology

However, in the above two coherent detection methods, there are the following problems: the relative signal-to-noise ratio of the broadband detector is low; The source is bulky, resulting in an uncompact system, etc.

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