A temperature-free and cross-sensitive fiber optic curvature sensor with high sensitivity and can determine the bending direction

Abstract

The invention discloses high-sensitivity fiber curvature sensor capable of discriminating the bending direction and free of cross temperature sensitivity. The sensor comprises a broadband light source, a first single mode fiber, a first welding point, a first thin core fiber, a first graphene film, a thin-core super long period fiber grating, a second graphene film, a second thin core fiber, a second welding point, a second single mode fiber and a sepctrometer, wherein the broadband light source is connected with the first single mode fiber, the connecting points between the first single mode fiber and the first thin core fiber form the first welding point, the first and second graphene films wrap the first and second thin core fibers at the two ends of the thin-core super long period fiber grating without interval respectively, the connecting point between the second thin core fiber and the second single mode fiber for the second welding point, and the second single mode fiber is connected with the spectrometer. The resonant wavelength position and power intensity of the spectrometer are monitored in real time, so that the bending direction can be discriminated, and cross interference caused by temperature can be avoided in the high-sensitivity curvature measuring process.

Description

technical field [0001] The invention belongs to the technical field of optical fiber curvature measurement, and in particular relates to a temperature-free and cross-sensitive high-sensitivity optical fiber curvature sensor that can determine the bending direction based on a thin-core ultra-long period optical fiber grating. Background technique [0002] Optical fiber curvature sensing with high sensitivity and large dynamic measurement range plays a very important role in structural health monitoring, and changes in external ambient temperature are often an important cross-interference factor for high-precision curvature measurement; therefore, high sensitivity without temperature crossover Interfering curvature sensing is an essential requirement for engineering applications to a high standard. Compared with ordinary electrical sensors, optical fiber sensors have the advantages of no electromagnetic interference, strong corrosion resistance, easy manufacture, low cost, fas...

AI Technical Summary

Problems solved by technology

It can be seen that most of the above optical fiber curvature sensor structures use a single wavelength demodulation method to realize the measurement of optical fiber curvature; if the external environment temperature changes during the curvature measurement process, the spectrum of the structure will have a large or small drift phenomenon, crosstalk will inevitably occur, resulting in inaccurate curvature sensitivity measurement

In the process of measuring the curvature of optical fiber, it is often necessary to judge the bending direction of the optical fiber, and the refractive index distribution of the above-mentioned single optical fiber device is circularly symmetric and has no obvious directionality.

Therefore, the existing measurement methods cannot meet the needs of highly sensitive optical fiber curvature measurement, and there is often crosstalk; in addition, the inability to distinguish the bending direction is also an important factor limiting its development

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