Positioning method and system of fiber grating

Abstract

The invention discloses a positioning method and system of a fiber grating. The basic principle is based on a fiber grating wavelength demodulation device of a tunable light source, due to the fact that the tunable light source has a wavelength constant-speed linear scanning characteristic, the wavelength scanning order of the tunable light source is set, namely reciprocating scanning is carried out once respectively with a short wave as a start point and with a long wave as a start point, the practical central wavelength of the fiber grating and the difference between a calculation wavelength obtained through wavelength scanning and the practical wavelength can be calculated, and accordingly the distance between the fiber grating to be detected and the wavelength demodulation device can be obtained. The fiber grating is laid on a device with the temperature or a stress point to be detected, due to the positioning system, wavelength demodulation is carried out, meanwhile, positioning information, accurate wavelength information, corresponding temperature information and strain information and other parameters can be obtained, the structure of a fiber grating demodulation system is greatly simplified, and system cost is reduced due to the fact that an OTDR technique is needless.

Description

technical field [0001] The invention belongs to the technical fields of optical fiber sensing and optical measurement, and in particular relates to a positioning method and system for an optical fiber grating. Background technique [0002] FBG (Fiber Bragg Grating, Fiber Bragg Grating) has the characteristic that the reflection wavelength changes linearly with external factors such as temperature and stress. Therefore, monitoring the shift of FBG reflection wavelength can measure the change of external parameters, and its detection ability is not affected by the light source. Influenced by factors such as power fluctuations, fiber bending loss, and detector aging, it is very suitable for long-term safety monitoring, especially its wavelength encoding characteristics and the advantages of quasi-distributed measurement on a single fiber are unmatched by other sensors , has broad application prospects. [0003] In some temperature measurement and alarm situations, such as the ...

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Problems solved by technology

[0005] The realization of OTDR technology requires the support of complex and expensive control circuits composed of electro-optic modulators and function generators, which are expensive and suitable for occasions with very high positioning accuracy (such as positioning accuracy <1 meter); but in most distributed In the field of sensing systems, the positioning accuracy requirements are not very high. Adding the OTDR function will increase the cost of the entire system, which greatly limits the popularization and application of distributed sensing systems.

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