A fiber Bragg grating demodulation system and method

Abstract

The invention provides a fiber Bragg grating demodulation system and method, which include sequentially connected and stably arranged: a light source, an optical circulator, a fiber Bragg grating, and an interferometer array; a light source for emitting broadband light and passing through the circulator The first port enters, and the second port outputs to the fiber Bragg grating; the fiber Bragg grating is used to receive the light of the light source and reflect it, and the reflected light enters the third port from the second port of the optical circulator and outputs it to the interferometer array for interference The sensor array, including multiple interferometers, is used to receive the light transmitted by the fiber Bragg grating from the optical circulator, convert the wavelength information of the light into intensity information, and use the intensity information to demodulate the fiber Bragg grating through compressed sensing technology. It is proposed to use an interferometer array containing multiple interferometers to sample the echo signal in space to improve the demodulation speed; the idea of ​​compressed sensing is introduced to reduce the requirements for the number of interferometer arrays and reduce the cost through sampling randomization.

Description

technical field [0001] The invention relates to the technical field of fiber Bragg grating demodulation, in particular to a fiber Bragg grating demodulation system and method. Background technique [0002] Optical fiber sensors are widely used in temperature sensing, curvature sensing and other fields because of their high sensitivity, strong anti-interference ability, and variable optical fiber shape. Among them, fiber Bragg gratings can process multiple sensors on one optical fiber because of their mature manufacturing process. Sensitive points and other advantages are the most widely used in fiber optic sensors. [0003] At present, the fiber Bragg grating technology is relatively mature. The fiber Bragg grating is a grating whose refractive index changes periodically along the light propagation direction in the optical fiber by using photolithography technology after the traditional communication optical fiber is doped and hydrogen-loaded. Each refractive index The chan...

AI Technical Summary

Problems solved by technology

Wavelength scanning demodulators generally use variable-wavelength lasers or variable-cavity wavelength identifiers. This type of device uses PZT or MEMS devices to drive the change in the distance between the front and rear reflection surfaces of the resonant cavity, and also uses electro-optic or thermo-optic effects to change the resonant cavity. The refractive index of the medium changes the optical length, and the light wavelength in the optical path is periodically scanned to convert the reflected light of the fiber Bragg grating into a pulse train in time series. When the wavelength of the reflected light of a certain grating changes, the return time of the pulse changes, and then To obtain the sensing quantity, this method requires a full spectral range scan for each measurement, so the measurement speed is slow

The second is to use a spectrometer to collect all spectral information in the spectral range at the same time. Although the demodulation speed is fast, the spectrometer is expensive. This method is generally used in the laboratory

The disadvantages are: (1) Each measurement needs to scan the entire spectrum, and the measurement speed is slow. At present, the general measurement frequency of commercial demodulators is below 100 Hz. In the field of robotics / wearables, the sampling frequency / return rate of joint angles is often required to be in KHz The above is even higher; (2) Due to the use of variable precision optical devices, this type of interrogator has high cost, is not suitable for miniaturization and is difficult to adapt to all working conditions

The disadvantages are: (1) The price of the spectrometer is very expensive, and this solution is generally only used in the laboratory

(2) The general spectral resolution of commonly used spectrometers is not as high as that of the first method

[0008] Therefore, there is a lack of a fiber Bragg grating demodulation method with fast measurement speed and low cost in the prior art

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