Device and method for eliminating polarization fading in OFDR

Abstract

The invention relates to a device and a method for eliminating polarization fading in OFDR. The device comprises a linear sweep frequency laser device, a polarization maintaining optical fiber beam splitter, a primary interferometer, an auxiliary interferometer, a data acquisition card and a computer, wherein the primary interferometer is used for making sweep frequency laser entering the primaryinterferometer undergo beat-frequency interference, so as to generate a first beat-frequency signal; the auxiliary interferometer is used for making sweep frequency laser entering the auxiliary interferometer undergo beat-frequency interference, so as to generate a second beat-frequency signal, and the second beat-frequency signal is converted to serve as an external clock of the high-speed data acquisition card; and the data acquisition card samples the first beat-frequency signal at equal frequency domain intervals under the trigger of the external clock. The device adopts polarization maintaining optical fibers and polarization maintaining optical fiber devices in the main optical path, a main interferometer and an optical fiber to be tested. Thus, a polarization state of an interference signal is strictly controlled in an optical path of the main interferometer as slow axis alignment and fast axis cut-off, and the polarization fading phenomenon is eliminated fundamentally. The stability and accuracy of the device are significantly improved in breakpoint detection, loss measurement and distributed temperature strain sensing.

Description

technical field [0001] The invention relates to the technical field of optical fiber sensing, more specifically, to a device and method for eliminating polarization fading in OFDR. Background technique [0002] OFDR technology is a distributed optical fiber measurement and sensing technology widely used in optical communication, aerospace, civil engineering, energy and power and other fields. The single-mode optical fiber in the OFDR system has birefringence, which will cause the polarization state of the output light in the optical fiber link to fluctuate, resulting in polarization fading. The basic principle of OFDR technology is optical heterodyne detection, which is to obtain the beat frequency interference signal of signal light and reference light. The specific performance of the polarization fading phenomenon is that the amplitude of the beat frequency interference signal of the signal light and the reference light fluctuates randomly, and even the beat frequency int...

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Problems solved by technology

However, the optical path needs to be adjusted in the early stage, and when the external environment changes, the best matching polarization state of the reference light and the signal light may change, thus making the effect of suppressing polarization fading unstable

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