Multimode fiber strain sensor with high sensitivity and measuring system

Abstract

The present invention relates to a chiral multimode fiber strain sensor with high sensitivity and a strain measuring system belonging to the technical field of fiber strain measurement. An existing fiber strain sensor is composed of a single mode fiber, a multimode fiber and a single mode fiber by fusion splicing, and has low measuring sensitivity. The multimode fiber strain sensor provided by the invention is composed of a single mode fiber, a twisted chiral multimode fiber and a single mode fiber by fusion splicing. A preparation method for the chiral multimode fiber includes the steps of fixing two ends of the multimode fiber through a fixture, heating the middle region and twisting simultaneously, and cooling to acquire the chiral multimode fiber. The strain measuring system includes the multimode fiber strain sensor with high sensitivity, a broadband light source, a spectrum analyzer and a signal processor. The broadband light source connects the fiber strain sensor with high sensitivity, the output end of the sensor connects the spectrum analyzer, and the signal processor analyzes an output spectrum and displays a measuring result. Compared to a traditional fiber strain measuring method, the multimode fiber strain sensor with high sensitivity is simple in preparation, is strong in anti-interference capability, and has highest sensitivity.

Description

technical field [0001] The invention belongs to the technical field of optical fiber strain measurement, and more specifically relates to the preparation of a highly sensitive multimode optical fiber strain sensor. Background technique [0002] Accurate fiber optic strain measurement is important in fiber optic communication and fiber optic sensing systems. [0003] In order to meet the demand for high-precision measurement in many application fields such as large-scale structural health monitoring of buildings and early warning of natural disasters such as earthquakes, people have done a lot of research on strain detection of structures, using various measurement technologies such as electrical sensing. However, due to the influence of electromagnetic interference, chemical corrosion, and humid environment in this traditional measurement method, the electrical measurement method has many shortcomings in terms of long-term measurement, real-time performance, and high precisi...

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Problems solved by technology

However, the sensitivity of the above methods to measure the strain is not more than 10pm / με

For the measurement of small deformation, the accuracy of the demodulation equipment is highly dependent, and the requirements for high-precision measurement cannot be achieved

In recent years, some researchers have proposed the use of double annular cavity to realize the vernier effect to improve the sensitivity of strain measurement, and achieved a sensitivity of 40pm / με, but the measurement range is only 10με, and the structure is complex and easily disturbed

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