A Fiber Bragg Grating Distortion Spectrum Demodulation Method

Abstract

The invention relates to a method for demodulating a distorted spectrum of an optical fiber grating. First, a sampled spectrum is obtained; then a theoretical model of the distorted spectrum is constructed by using a quasi-super-Gaussian function with asymmetric properties, and the demodulation principle based on reflection spectrum reconstruction is used to design a response to the distorted spectrum. Adaptive demodulation model; Finally, the adaptive demodulation model for distorted spectrum is realized by using particle swarm optimization algorithm, and the sampling spectrum is optimized to find the central wavelength and distortion parameters of FBG, so as to solve the problem of difficult demodulation due to FBG spectral distortion Case. The invention can not only ensure the high-precision demodulation of the normal spectrum, but also can perform self-adaptive demodulation of the distorted spectrum to the greatest extent.

Description

technical field [0001] The invention relates to the field of fiber gratings, in particular to a method for demodulating a fiber grating distortion spectrum. Background technique [0002] Fiber Bragg Grating (FBG) sensing, as a new type of sensing technology developed rapidly in recent years, has been applied in various engineering fields due to its advantages of anti-electromagnetic interference, linear sensing, and easy multiplexing and networking. In sensor monitoring, especially in the field of structural health monitoring, it has great application value. [0003] As the structural form and functional control of the structural health monitoring system presents a trend of complex, diversified and intelligent development, as the most important front-end input of the monitoring system, the long-term reliability and stability of the FBG sensor network plays an important role in the monitoring performance of the system. critical use. In the structural health monitoring syste...

AI Technical Summary

Problems solved by technology

In the structural health monitoring system, the actual engineering application of FBG sensor network generally has the characteristics of large distribution area, long service life, and complex material properties. Under the dual effects, coupled with the limitations of construction technology and structural design, FBG sensors will inevitably experience varying degrees of performance degradation

When the performance of the FBG sensor declines or breaks, it will directly have an adverse impact on the structural health monitoring system: on the one hand, the failure of the local FBG leads to the inability of the sensor network to accurately collect measurement data, which seriously affects the follow-up monitoring and evaluation results, causing the monitoring system to damage the structure. False positives and negative negatives of health status; on the other hand, FBG sensors are usually embedded in the structure on a large scale in the form of a network. If a single FBG sensor needs to be replaced, the entire structure needs to be destroyed, or even the entire optical cable needs to be replaced, which will inevitably cause huge damage. economic loss

Therefore, the FBG performance degradation affects the reliability of the sensor network began to attract people's attention

[0004] The degradation of FBG performance will cause different degrees of spectral distortion, light intensity attenuation, spectral overlap and other phenomena. These degraded spectra are difficult to be demodulated, so that the FBG loses its sensing ability.

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