Interference distributed optical fiber acoustic sensing device and sensing method

Abstract

The invention discloses an interference distributed optical fiber acoustic sensing device. The device includes a light source (1), a polarization controller (2), a polarization beam splitter (3), a modulation signal generating device (5), a first light amplifier (7), a first 1*2 fiber coupler (8), a time-delay fiber (9), a second 1*2 fiber coupler (10), a fiber circulator (11), a sensing fiber (12), a second light amplifier (13), a micro-reflective grating array (14), a second photodetector (15), an acquisition card (16), and a signal processing device (17) which are connected in sequence. Compared with the prior art, the device and the method can increase rapidity and simplicity of sound sensing demodulation, and different sensing spatial resolution requirements can be satisfied through flexible arrangement of spacing of a micro-reflective grating.

Description

technical field [0001] The present invention relates to the technical field of coherent optical time domain reflection and signal demodulation, in particular to an interference distributed optical fiber acoustic sensing device and sensing method based on micro-reflection gratings and double-sweep frequency modulation pulses. Background technique [0002] Phase-sensitive Optical Time Domain Reflectometer (Phase-sensitive Optical Time Domain Reflectometer, ) sensing technology has a wide range of applications and demands in building structure health monitoring, mineral detection, submarine optical cable monitoring, and underwater monitoring. Phase-sensitive optical time-domain reflection sensing technology injects light pulses, analyzes the back Rayleigh scattered light signals along the optical fiber, and obtains the optical phase information of the sensing optical fiber, so as to detect the optical fiber caused by external vibration and acoustic signals in real time. The p...

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Problems solved by technology

Due to the random distribution of scattering points in the fiber, the low Rayleigh scattering coefficient, and the use of simple single-frequency pulses, it is difficult for the traditional phase-sensitive optical time-domain reflection sensing technology to achieve high-precision detection of external acoustic vibrations. Full-information waveform measurement including amplitude, frequency and phase, which limits the scope of application of phase-sensitive optical time-domain reflectometry in practical engineering applications

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