Cavity ring-down fiber grating sensing demodulating device based on calibrated fiber grating

Abstract

A cavity ring-down fiber grating sensing demodulating device based on a calibrated fiber grating is characterized in that an optical switch is connected between a dual-wavelength tunable narrow linewidth laser and an optical coupler I. An optical fiber annular cavity is sequentially connected with the optical coupler I, the calibrated fiber grating, a sensing fiber grating, an erbium-doped optical fiber amplifier, an optical circulator and an optical coupler II in the clockwise direction. The optical circulator is further connected with a denoising fiber grating. An optical coupler III is connected with the optical coupler II. An optical fiber I and an optical fiber II are both connected with the optical coupler III. A photoelectric detector I is connected between the optical fiber I and a signal processor. A photoelectric detector II is connected between the optical fiber II and the signal processor. According to the cavity ring-down fiber grating sensing demodulating device based on the calibrated fiber grating, temperature and strain of the calibrated fiber grating are accurately controlled, cavity ring-down time constant difference of sensing wavelength and calibrating wavelength is measured so that the temperature or the strain of the sensing fiber grating can be obtained, and influence on system performance by light source wavelength shift and environment factors is eliminated.

Description

technical field [0001] The invention relates to a cavity ring-down optical fiber grating sensor demodulation device based on a calibrating optical fiber grating. Background technique [0002] Cavity ring-down technology is mainly used for testing in the field of spectroscopy, and has trace detection capabilities. In recent years, fiber grating stress sensing based on cavity ring down has been proposed. However, the cavity ring-down fiber grating demodulation technology that has been proposed so far only uses the sensing fiber grating. A disadvantage of such systems is that system performance is limited not only by environmental factors such as temperature or strain, but also by light source wavelength drift. Environmental factors cause changes in the refractive index and cavity length of the fiber ring cavity, resulting in changes in the ring-down time constant of the cavity, causing demodulation errors in the fiber grating sensing system, and ultimately affecting the meas...

AI Technical Summary

Problems solved by technology

However, the cavity ring-down fiber grating demodulation technology that has been proposed so far only uses the sensing fiber grating

The disadvantage of such systems is that system performance is limited not only by environmental factors such as temperature or strain, but also by light source wavelength drift

Environmental factors cause changes in the refractive index and cavity length of the optical fiber ring cavity, resulting in changes in the ring-down time constant of the cavity, resulting in demodulation errors in the fiber grating sensing system, and ultimately affecting the measurement accuracy of external parameters

Light with different wavelengths has different transmittance after passing through the fiber grating. Therefore, the wavelength drift of the light source will also cause the change of the ring-down time constant of the cavity, which will cause the demodulation error of the fiber grating sensing system, and finally affect the measurement accuracy of external parameters.

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