Distributed weak grating array sensing system and method capable of eliminating effects of polarization fading

Abstract

The present invention discloses a distributed weak grating array sensing system and method capable of eliminating the effects of polarization fading. The method comprises the steps of: introducing first pulsed light modulated by a first modulator into a coupler; dividing the pulsed light into two pulsed light beams, wherein one pulsed light beam is coupled to the other pulsed light beam by a polarization beam splitter after passing through a time-delay fiber having a length corresponding to the width of the pulsed light beam; modulating, by a second modulator, long pulsed light having a pulsewidth twice the width of the first pulsed light; then coupling the first and second pulsed light by a coupler into a group of detection dual pulsed light; enabling the dual pulsed light to enter a grating array through a circulator; wherein the reflected light of the dual pulsed light on adjacent gratings are superposed to have interference, then the interference light enters a photoelectric detector through the circulator and an acquisition card perform data acquisition and analysis. The system and method can effectively solve the influence of polarization fading and ensure high response frequency.

Description

technical field [0001] The invention relates to the technical field of optical fiber sensing, in particular to a distributed weak grating array sensing system and method for eliminating the influence of polarization fading. Background technique [0002] Optical fiber sensing technology is a brand-new technology developed from the 1970s. With the practical application of optical fibers and the development of optical communication technology, optical fiber sensing technology has developed rapidly in a diversified manner. When light is transmitted in the optical fiber, due to the influence of external disturbance, temperature, strain, displacement and other environmental factors on the optical fiber, the polarization state, power, wavelength, phase and other parameters of the optical signal will change. By detecting these parameters of the light in the optical fiber, the change information of the environment around the optical fiber can be obtained, thereby realizing sensing. ...

AI Technical Summary

Problems solved by technology

For the traditional grating array vibration measurement, the pulse signal is affected by external disturbances during the transmission process. When the signals are interfered and superimposed, the polarization state of the two superimposed interference signals may be approximately vertical or even vertical due to the change of the polarization state. The visibility of the interference signal obtained in this way is reduced, and the detection sensitivity is reduced, especially when the polarization states are completely orthogonal, which will lead to the failure of the detection of the interference signal

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