Patent ID: 11933646
Assignee: WUHAN UNIVERSITY OF TECHNOLOGY
Field: Measurement (Instruments)
Classification: CPC G  H  Y | IPC G  H

Claim 6:
7. A demodulation method of the interferometric demodulation system for the large capacity fiber grating sensing network according to claim 1, wherein:
S1: outputting the nanoscale wide-spectrum optical signal from the nanoscale wide-spectrum light source;
S2: using the pulse optical modulator to modulate the nanoscale wide-spectrum optical signal into a pulse optical signal and amplify the pulse optical signal power;
S3: making the amplified pulse optical signal entering the reference grating and the grating array sensing network through the optical circulator in a sequence, wherein: an initial center wavelength of the reference grating is known, and is packaged in a temperature-isolated and a shock-isolated environment to ensure that a center wavelength is unchanged; since a spectral width of the pulse optical signal covers a working bandwidth of the FBG in the grating array sensing network, a return signal of the each FBG under a single pulse is a respective reflected spectral signal, and an optical signal reflected back by the grating array sensing network is output to the optical amplifier by the optical circulator to amplify the optical reflection signal with the sensing information and then send to the Mach-Zehnder interferometer;
S4: making the each FBG of the grating array sensing network returning optical signals and then entering the Mach-Zehnder interferometer, and being divided into two paths through the 1×2 coupler, to ensure an interference of the two paths of the optical signals, an arm length difference N of the two paths of optical fiber arms is less than the coherence length of the single FBG in the grating array sensing network; and
S5: determining an arrival time of a reflected optical signal through collected three-way reflected light by the embedded signal processor, thereby obtaining a spatial position of the each FBG in the grating array sensing network, and obtaining a central wavelength variation of the each FBG by a phase wavelength demodulation algorithm, and further demodulating a central wavelength of the each FBG; the central wavelength variation is proportional to a temperature, a stress and a vibration of the object to be measured, and further realizing a distributed sensing of physical quantities.