Phase-light time domain reflection device and method based on heterodyne detection phase demodulation

Abstract

The invention relates to the field of optical fiber sensing, specifically a phase-light time domain reflection device and method based on heterodyne detection phase demodulation. The device consists of a narrow linewidth laser, an optical fiber coupler with a coupling model of 1*2, a polarization controller, a sound-light modulator, an erbium-doped optical fiber amplifier, a narrow-band optical fiber filter, a first variable optical attenuator, a three-port circulator, a sensing optical fiber, an optical fiber coupler with a coupling model of 2*1, a photoelectric detector, a signal collection and processing module, an arbitrary waveform generator, a power amplifier, and a second variable optical attenuator. The device and method enable the heterodyne detection phase demodulation to be combined together, achieve external vibration sensing through direct phase demodulation, and are higher in sensitivity. In addition, the device and method employ a brand new direct phase modulation method to sense the external vibration, so the positioning method, compared with a conventional method, of each vibrating point is different.

Description

technical field [0001] The invention relates to the field of optical fiber sensing, in particular to a phase optical time domain reflection device and method based on heterodyne detection and phase demodulation. Background technique [0002] Distributed optical fiber sensing technology has been widely used for its advantages of continuous sensing of temperature, strain and other parameter changes at any point along the optical fiber, optical fiber integrating signal sensing and transmission, and convenient for long-distance sensing and large-scale networking. All aspects of the national economy and people’s daily life, including structural safety monitoring of buildings, bridges, dams, tunnels, river embankments, aircraft, ships, factory equipment, etc., leak detection in dangerous places such as oil pipelines and high-voltage lines, and border intrusion Real-time monitoring and fault point detection of communication optical cables. [0003] Optical time domain reflection t...

AI Technical Summary

Problems solved by technology

However, the above methods all use the light intensity change caused by the phase change for vibration sensing, rather than directly using the phase change for vibration sensing. Considering that the sensitivity of the intensity-modulated optical fiber sensor is lower than that of the phase-modulated optical fiber sensor, the above-mentioned The method has great limitations in the detection of weak vibration signals

Images