Frequency multiplexing and demultiplexing multichannel grating demodulation device and method

Abstract

The invention discloses a frequency multiplexing and demultiplexing multichannel grating demodulation device and method. The sensing device comprises a linear sweep frequency laser, a first optical fiber coupler, a second optical fiber coupler, an optical fiber circulator, an optical fiber beam splitter, a plurality of acousto-optic frequency shifters, an FBG (Fiber Bragg Grating), a photoelectric detector, a data acquisition card and a computer. Based on a coherent detection technology, multi-channel signals are subjected to frequency multiplexing, photoelectric signal conversion is realized in a single photoelectric detector, a single-channel acquisition card is used for analog-to-digital conversion, an FPGA in the acquisition card is used for realizing FFT operation, and a physical position and a spectral signal of a to-be-detected FBG are output. And finally, performing a series of data processing operations such as window inverse Fourier transform and the like in calculation to obtain temperature and strain fast demodulation. According to the invention, multi-channel fast fiber grating demodulation can be realized, sweep-frequency light source multiplexing and single-channel acquisition are realized, and the cost of the demodulation device is greatly saved on the premise of meeting the performance.

Description

technical field [0001] The invention relates to the technical field of optical fiber sensing, in particular to a multi-channel grating demodulation device and method for frequency multiplexing and demultiplexing. Background technique [0002] High-speed strain measurement, impact and vibration testing have a wide range of requirements. Conventional means include electronic strain gauges and fiber gratings; electronic strain gauges are not suitable for special fields due to electrical and electromagnetic compatibility problems. Fiber Bragg grating strain measurement has the characteristics of small size, light weight, high sensitivity, strong anti-interference ability, etc., and is especially suitable for monitoring high-speed strain, impact and collision. [0003] At present, fiber optic sensing demodulation technology is developing rapidly, among which FBG (Fiber Bragg Grating, Fiber Bragg Grating) demodulation based on tunable laser light source has attracted more attenti...

AI Technical Summary

Problems solved by technology

The main problem faced by this traditional solution is that the spatial resolution is not high, and a large number of FBGs with different central wavelengths are required as sensors; in multi-channel multiplexing, the optical power of the light source needs to be divided into multiple channels, sacrificing the power of the light source, thus The signal-to-noise ratio of the grating spectrum decreases, which affects the measurement range and accuracy

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