Method for measuring spontaneous Brillouin scattering based on super structured fiber grating filter

A Brillouin scattering and fiber grating technology, applied in the field of sensing, to achieve the effect of adjustable center wavelength, low insertion loss, and good roll-off characteristics

Inactive Publication Date: 2010-03-10
PLA UNIV OF SCI & TECH
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Problems solved by technology

Fiber Bragg Gratings are widely used to make all-optical filters required for various sensing and communication, but traditional Fiber Bragg Grating filters cannot meet the needs of BOTDR, because Rayleigh and Brillouin scatte

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  • Method for measuring spontaneous Brillouin scattering based on super structured fiber grating filter
  • Method for measuring spontaneous Brillouin scattering based on super structured fiber grating filter
  • Method for measuring spontaneous Brillouin scattering based on super structured fiber grating filter

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Embodiment Construction

[0014] First, the reconfigurable-equivalent chirp (REC) technology is used, and according to the characteristics of the Brillouin signal, the index of the superstructure fiber grating filter is determined: the central wavelength of the filter λ = 1543.8nm, and the distance between double peaks d = 0.176 nm. make out figure 2 For the superstructure fiber grating filter shown, the curve is the reflection spectrum line measured by using a wide-spectrum light source.

[0015] On the basis of successfully making bimodal filters, the BOTDR scheme based on dual light sources and grating filtering is as follows image 3

[0016] shown. Since the narrow linewidth light source will cause coherent Rayleigh noise, in order to obtain the Rayleigh scattering reference and Brillouin scattering signals, we adopted a dual light source scheme.

[0017] The narrow-linewidth laser used to generate Brillouin scattering is injected into the erbium-doped fiber amplifier through the external mod...

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Abstract

The invention discloses a method for measuring spontaneous Brillouin scattering based on a super structured fiber grating filter, which inhibits coherent Rayleigh noise by the method which uses the distribution of a narrow line width to feedback a fiber optic laser and a wide band laser to obtain strength ratio of a Brillouin signal and a Rayleigh signal; the method comprises the following steps:firstly, the generated narrow line width pulsed light is fed back to a detected fiber after polarization control according to the length of the fiber; a back reflection signal enters a filter bank through a circulator port (4) and respectively regulates the adjustable super structured fiber grating filter, filters a Rayleigh signal to the largest extent, extracts a spontaneous Brillouin scatteringsignal, feeds the spontaneous Brillouin scattering signal into a highly sensitive photoelectricity conversion module and a signal processing module, and detects the intensity of the spontaneous Brillouin signal through data accumulation and wavelet-de-noising treatment; secondly, the pulsed light generated by the wide band laser passes through a rear-end module the same as in the first step to measure the Rayleigh scattering signal; and finally, the data measured at two times are processed on a computer to display the fiber temperature and stress, which solves the problem of measuring methodof the fiber spontaneous Brillouin signal.

Description

technical field [0001] The invention relates to a method for measuring optical fiber spontaneous Brillouin scattering signals based on a superstructure optical fiber grating filter (also known as a double-peak filter), which is mainly used for measuring optical fiber spontaneous Brillouin scattering signals and belongs to the field of sensing technology. Background technique [0002] The design and fabrication of filter is the key to the measurement of optical fiber self-Brillouin scattering signal. Due to the characteristics of the Brillouin signal (the scattering spectrum in the fiber is as figure 1 As shown), it is difficult to obtain matching filters on the market. At present, interferometers are mainly used to realize the existing schemes. However, the commonly used fiber-optic M-Z interferometers have problems such as poor stability and difficult adjustment. They can only be used in some experiments. It is used in a room environment, and the F-P interferometer is not ...

Claims

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Application Information

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IPC IPC(8): G01K11/32G01L1/24G02B6/34G01K11/3206G01K11/322
Inventor 张永智王荣徐智勇浦涛
Owner PLA UNIV OF SCI & TECH
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