Stress-packaging-free temperature-sensing optical fiber cable and preparation method thereof

Abstract

A stress-packaging-free temperature-sensing optical fiber cable and a preparation method thereof are provided, wherein the stress-packaging-free temperature-sensing optical fiber cable comprises: an ultra-weak optical fiber grating array positioned in the center; fiber bundles uniformly distributed around the ultra-weak optical fiber grating array in parallel, wherein the ultra-weak optical fibergrating array and the fiber bundles are freely combined; a metal tube wrapping the peripheries of the ultra-weak optical fiber grating array and the fiber bundles along the axial direction; and a reinforcement which is twisted and surrounded in a spiral form around the metal tube. According to the stress-packaging-free temperature-sensing optical fiber cable of the invention, the ultra-weak optical fiber grating array and the multiple fiber bundles are freely combined, then the metal tube is adopted for direct packaging, the extra length of the optical fiber is absorbed by adoption of a beam expanding effect after the optical fiber rebounds, the friction between the optical fiber and the tube wall of the metal tube is reduced, accumulated distribution of the extra length is inhibited, batch calibration is facilitated, the linear correlation degree of a temperature curve of the optical fiber is up to more than 0.999, the temperature sensitivity fluctuation is less than 0.3pm / DEG C, andthe temperature measurement precision of the optical cable is improved.

Description

technical field [0001] The invention relates to the field of optical fiber optic cable temperature sensing, in particular to a stress-free packaged temperature-sensitive optical fiber optic cable and a preparation method thereof. Background technique [0002] Optical fiber sensing can realize reliable monitoring of physical quantities such as strain and temperature, and has wide demand and good application prospects in geotechnical engineering, bridges, tunnels, perimeters and other fields. At present, the main optical fiber sensing technologies include Brillouin scattering-based optical fiber sensing technology (BOTDR / BOTDA), optical frequency domain reflectometry (OFDR), fiber Bragg grating (FBG / wFBG) sensing technology (FBG / wFBG), etc. However, in actual measurement, there is inevitably the problem of cross-sensitivity between temperature and strain. Although BOTDR / BOTDA can separate temperature and strain to a certain extent through algorithm processing, the measurement...

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Problems solved by technology

[0008] Aiming at the problems of complex structure, difficult automatic production, and poor temperature measurement accuracy of the existing temperature-measuring optical cable, the present invention proposes a stress-free packaged temperature-sensing optical fiber cable and its preparation method. After the fibers are freely bundled, they are directly packaged in a metal tube, and the beam expansion effect after the rebound of the fiber is used to absorb the excess length of the optical fiber, reduce the contact between the optical fiber and the metal tube, suppress the cumulative distribution of the excess length, and facilitate batch calibration. The linear correlation degree of the temperature curve reaches above 0.999, and the temperature sensitivity fluctuation is less than 0.3pm / °C, which improves the temperature measurement accuracy of the optical cable; in addition, the optical fiber cable of the present invention has a simple structure and is easy to be prepared in batches by machines, and has wide application in the field of fiber grating stress and strain sensing. application prospects

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