Method for precisely estimating signal to noise ratio of EOM (Electro-Optic Modulator) pulse modulated BOTDR (Brillouin Optical Time Domain Reflectometer)

A technique of pulse modulation and accurate estimation, applied in the direction of instruments, etc., can solve the problems that affect the estimation accuracy of the signal-to-noise ratio and not be considered, and achieve the effect of improving the estimation accuracy

Inactive Publication Date: 2012-07-25
NANJING UNIVERSTIY SUZHOU HIGH TECH INST +1
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Problems solved by technology

Among the existing BOTDR SNR estimation methods (H.Ohno, H.Naruse, N.Yasue, Y.Miyajima, H.Uchiyama, Y.Sakairi and Z.X.Li. "Development of highly stable BOTDR strain sensor employing microwave heterodyne detection and tunable electric oscillator, "Proc.SPIE4596, 74-85(2001)), considers that pulsed light is ideal, and does not consider the influence of continuous leakage light caused by finite extinction ratio, which affects the accuracy of signal-to-noise ratio estimation

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  • Method for precisely estimating signal to noise ratio of EOM (Electro-Optic Modulator) pulse modulated BOTDR (Brillouin Optical Time Domain Reflectometer)
  • Method for precisely estimating signal to noise ratio of EOM (Electro-Optic Modulator) pulse modulated BOTDR (Brillouin Optical Time Domain Reflectometer)
  • Method for precisely estimating signal to noise ratio of EOM (Electro-Optic Modulator) pulse modulated BOTDR (Brillouin Optical Time Domain Reflectometer)

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Embodiment Construction

[0027] The present invention will be further described and described below in conjunction with the accompanying drawings.

[0028] figure 1 A schematic diagram of the BOTDR system used for the experiment is shown. The output light of the narrow-linewidth laser 01 is divided into two paths by the polarization-maintaining fiber coupler 02, one path is incident on the EOM03, and the pulsed light is generated by the pulse signal generator 04, and then the pulsed light is amplified by the erbium-doped fiber amplifier 05 and passed through the circulator 06 It is injected into the sensing fiber 07 to generate backward self-published Brillouin scattered light; the other path passes through EOM08 and microwave signal source 09 for frequency shifting, and the polarization scrambler 10 is used to reduce polarization noise, and the local reference light and self-published Brillouin scattered light The light is coherent through the coupler 11, the photodetector 12 is used for photoelectr...

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Abstract

The invention relates to a method for precisely estimating the signal to noise ratio of an EOM (Electro-Optic Modulator) pulse modulated BOTDR (Brillouin Optical Time Domain Reflectometer), which comprises the steps of: taking EOM modulated pulse as overlapping of ideal pulse light and continuous leakage light to determine the peak value power Pp and leakage power Pb of the modulated pulse light, the pulse width w and the length L of a sensing optical fiber, wherein the ideal pulse light peak value power is Pp-Pb, the constant power of the continuous leakage light is Pb and the EMO extinction ratio is ER=Pp/Pb; and the power of the self-releasing Brillouin scattering spectrum excited by the ideal pulse light at the central frequency meets a certain formula. The method takes the pulse light modulated by an electro-optical intensity modulator as the overlapping of the pulse light with the ideal extinction ratio and the leakage light, and takes the optical fiber as a linear system, so as to respectively obtain the self-releasing Brillouin scattering light generated by the pulse light with the ideal extinction ratio and the leakage light, and investigates the impact of the leakage light on root-mean-square error of a power curve when a signal is obtained by the coherent detection manner so as to acquire the signal to noise ratio of the BOTDR system.

Description

technical field [0001] The invention relates to the field of optical fiber sensing, and is used in a Brillouin optical time domain reflectometer (Brillouin optical time domain reflectometer, BOTDR) that uses an electro-optical modulator (electro-optical modulator, EOM) to modulate pulses, and the BOTDR system signal-to-noise Accurate estimation of signal-to-noise ratio (SNR). Background technique [0002] The working principle of BOTDR is that the frequency shift and power of Brillouin scattered light are related to temperature and stress. The temperature and stress measurement is realized by measuring the frequency shift and power of the backward self-Buriouin scattered light generated when the pulsed light is transmitted in the optical fiber. The location of the measured temperature and strain is realized according to the time difference between the injection of the pulsed light into the optical fiber and the reception of the spontaneous Burrillouin scattered light. Due ...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01D18/00
Inventor 路元刚赵晓东张旭苹
Owner NANJING UNIVERSTIY SUZHOU HIGH TECH INST
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