Demodulation method, system and device for polarization interference optical fiber sensor

Abstract

The invention belongs to the technical field of optical fiber sensing, and in particular relates to a demodulation method, system, and device for a polarization interference optical fiber sensor, aiming to solve the problem that the existing polarization interference optical fiber sensor demodulation scheme has a measurement range subject to a spectral width of a light source Limitation and parasitic interference cause demodulation errors, resulting in poor demodulation robustness and applicability. The method includes collecting interference spectrum data under the initial external physical conditions; selecting the extreme point of the set phase and normalizing it; obtaining the initial value of the fitting coefficient; calculating the set wavelength / frequency position under the initial external physical conditions The initial value of the birefringence; collect the interference spectrum data after the initial external physical conditions change; use the waist point to select the fitting sample point; perform the least square fitting; calculate the set wavelength / Birefringence values ​​at frequency locations; difference between birefringence values ​​is computed and demodulated. The invention improves demodulation robustness and applicability.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing, and in particular relates to a demodulation method, system and equipment for polarization interference optical fiber sensors. Background technique [0002] The common polarization-maintaining optical fiber sensor sensing unit is a polarization-maintaining fiber. When light is transmitted along the fast axis and slow axis of the polarization-maintaining fiber, the phase difference will be generated due to the birefringence of the polarization-maintaining fiber. When the physical conditions such as gas pressure and hydrogen concentration change, the birefringence value of the sensing fiber changes, which will cause the phase difference of the two polarization modes to change, resulting in different degrees of shift in the overall polarization interference spectrum. By detecting the interference spectrum The measurement of the physical quantity can be realized by shifting or sensing th...

AI Technical Summary

Problems solved by technology

[0004] In order to solve the above problems in the prior art, that is, in order to solve the existing polarization interference optical fiber sensor demodulation scheme, the measurement range is limited by the spectral width of the light source and the demodulation error phenomenon caused by parasitic interference, resulting in demodulation robustness and applicability Poor problem, the first aspect of the present invention, proposes a kind of demodulation method that is used for polarization interference type optical fiber sensor, this method comprises:

Images