Irregular optical fiber grating group stress sensor based on wavelength and amplitude dual coding

Abstract

The invention discloses an irregular optical fiber grating group stress sensor based on wavelength and amplitude dual coding, belonging to the technical field of optical fiber sensors. The sensor comprises a broadband light source, a circulator, a single mode fiber, an apodized grating group, refractive index matching liquid, a spectrometer and a computer processing system. The apodized grating group consists of M*N apodized gratings which totally comprises M resonant wavelengths, each of the M resonant wavelengths has N same resonant wavelengths, but the N gratings have different refractive indexes; and the M*N gratings in the apodized grating group are irregularly distributed, i.e. each N gratings of M different resonant wavelengths can be crossed with any sequences, but every N gratings having same resonant wavelengths shall keep the ascending or descending sequence of refractive index in the entire grating group. With the irregular optical fiber grating group stress sensor based on wavelength and amplitude dual coding, the combination of wavelength coding and amplitude coding is adopted, the sensing range is effectively extended, and the sensing precision is enhanced, and the adoption of irregular apodized grating distribution mode can further eliminate the interference of harmonic peak side lobe.

Description

technical field [0001] The invention relates to the field of optical fiber sensing, in particular to an irregular optical fiber grating group stress sensor based on double coding of wavelength and amplitude. Background technique [0002] A fiber grating is a diffraction grating formed by periodically modulating the refractive index of the fiber core in a certain way, and is a passive filter device. Because fiber gratings have the advantages of small size, low splicing loss, full compatibility with optical fibers, and can be embedded in smart materials, and have the characteristics that the resonant wavelength is sensitive to external conditions such as stress, strain, temperature, reflectivity, and concentration, so in optical fiber Communication and sensing fields have been widely used. [0003] Changes in the external environment such as stress, strain, temperature, reflectivity, concentration, etc. will cause changes in the effective refractive index of the fiber or grat...

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Problems solved by technology

[0005] For the above-mentioned first sensor, too many wavelengths cannot be set, which limits the number of gratings, and limits the sensing range and sensing accuracy.

For the above-mentioned second sensor, the number of gratings should not be too many, because there are too many gratings, and the power contribution value of each grating is too small, which will also affect the sensing accuracy

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