WO2022064597A1 - Device and method for detecting trend of increase and decrease of microbending loss in optical fiber - Google Patents

Device and method for detecting trend of increase and decrease of microbending loss in optical fiber Download PDF

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WO2022064597A1
WO2022064597A1 PCT/JP2020/036026 JP2020036026W WO2022064597A1 WO 2022064597 A1 WO2022064597 A1 WO 2022064597A1 JP 2020036026 W JP2020036026 W JP 2020036026W WO 2022064597 A1 WO2022064597 A1 WO 2022064597A1
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optical fiber
measured
gawbs
microbend
increase
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PCT/JP2020/036026
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French (fr)
Japanese (ja)
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一貴 納戸
奈月 本田
博之 押田
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日本電信電話株式会社
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Priority to JP2022551492A priority Critical patent/JPWO2022064597A1/ja
Priority to PCT/JP2020/036026 priority patent/WO2022064597A1/en
Publication of WO2022064597A1 publication Critical patent/WO2022064597A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for

Definitions

  • Microbend may occur when water permeates the coating of the optical fiber.
  • the increase in the microbend loss due to immersion changes gradually, which is important in the maintenance of the optical fiber.
  • a method of detecting a loss due to a microbend there is a method of measuring a transmission loss using an OTDR (Optical Time Domain Reflectometer) or a light loss using an optical power meter.
  • OTDR Optical Time Domain Reflectometer
  • Hiroshi Amano "All about Access Networks", p. 52, Telecommunications Association, July 1, 2017.
  • Hiroshi Takahashi et al. "Branch Optical Fiber Loss Measurement Technology that Enables End-to-End Measurement of Optical Access Lines", NTT Technical Journal, December 2017, pp. 58-62.
  • the microbend loss may show a tendency to increase once and then decrease, and if there is no data on the change over time of the loss in the detection using the loss, it is not possible to know the tendency of the increase or decrease in the microbend loss at the time of loss measurement. .. Therefore, the transmission loss of the optical fiber tends to decrease only by the detection using the loss, and from the viewpoint of the transmission loss, the failure repair operation of the optical fiber without any problem in the service operation may occur.
  • the purpose of this disclosure is to detect an increase / decrease tendency of the microbend loss of an optical fiber in which microbend is generated, which does not require data on changes over time in order to reduce unnecessary repair operation of the optical fiber. And.
  • the device is Measure the forward Brillouin scattering (GAWBS) of the optical fiber to be measured in which the target microbend is generated, and measure it. Based on the characteristics around the peak of the forward Brillouin scattering, the tendency of increase / decrease in the microbend loss of the optical fiber to be measured is detected.
  • GAWBS forward Brillouin scattering
  • the method pertaining to this disclosure is Measure the forward Brillouin scattering of the optical fiber under test where the target microbend is generated, Based on the characteristics around the peak of the forward Brillouin scattering, the tendency of increase / decrease in the microbend loss of the optical fiber to be measured is detected.
  • This disclosure can detect an increase / decrease tendency of the microbend loss of an optical fiber in which microbend occurs on the spot even when there is no data of change with time. This makes it possible to reduce unnecessary failure repair operations using optical fibers due to microbend loss.
  • GAWBS As an example of GAWBS, (a) shows depolarized GAWBS and (b) shows polarized GAWBS.
  • An example of the spectral waveform of GAWBS is shown.
  • An enlarged view of one of the peaks in the spectral waveform of GAWBS is shown.
  • An example of the change over time of GAWBS is shown.
  • An example of the first system configuration in the first embodiment is shown.
  • a second system configuration example in the first embodiment is shown.
  • a third system configuration example in the first embodiment is shown.
  • An example of the microbend loss increase / decrease tendency detection method according to the first embodiment is shown.
  • An example of the first system configuration in the second embodiment is shown.
  • a second system configuration example in the second embodiment is shown.
  • a third system configuration example in the second embodiment is shown.
  • the first example of the microbend loss increase / decrease tendency detection method of 2nd Embodiment is shown.
  • a second example of the microbend loss increase / decrease tendency detection method of the second embodiment is shown.
  • a third example of the microbend loss increase / decrease tendency detection method of the second embodiment is shown.
  • FIG. 1 shows an example of GAWBS (Guided acoustic-wave Brillouin scattering).
  • GAWBS Guided acoustic-wave Brillouin scattering
  • the spectrum of GAWBS depends on the propagation loss of the sound wave, the main factor of which is the reflectance of the sound wave.
  • the reflectance of sound waves inside an optical fiber is affected by the acoustic impedance outside the optical fiber.
  • the acoustic impedance of an optical fiber changes in response to changes in the coating of the optical fiber.
  • the state of the coating of the optical fiber in which microbend is generated changes, and the acoustic impedance also changes with the change of the coating, and the spectrum of GAWBS changes.
  • the acoustic impedance outside the optical fiber decreases and the reflectance of the sound wave inside the optical fiber increases, the half-value width of the peak of the GAWBS spectrum decreases.
  • the present disclosure uses the change to detect an increasing / decreasing tendency of the microbend loss of the optical fiber in which microbend is generated.
  • FIG. 2 shows an example of the spectral waveform of GAWBS.
  • FIG. 3 shows an enlarged view of one of the peaks in the spectral waveform of GAWBS. It can be seen that the spectrum changes as the transmission loss increases due to the generation of microbends. Therefore, the present disclosure uses any combination of spectral changes in forward Brillouin scattering (GAWBS) as shown below to detect changes in the state of the optical fiber coating.
  • GAWBS forward Brillouin scattering
  • the microbend loss increases once and then decreases, but the peak frequency intensity of the GAWBS spectrum increases even after the microbend loss starts to decrease. ..
  • the intensity of the frequency of the peak of the spectrum of GAWBS is observed, and the increase / decrease tendency of the microbend loss is detected by the magnitude of the intensity by utilizing the fact that the intensity increases even after the decrease of the microbend loss. Aspects can be adopted.
  • the microbend loss increases once and then decreases, but the GAWBS spectral line width narrows even after the microbend loss starts to decrease.
  • the tendency of increase / decrease of the microbend loss is detected by the narrowness of the spectral line width of the GAWBS by utilizing the narrowing of the spectral line width of the GAWBS.
  • the line width can be calculated by approximating the spectrum with a Lorenz curve. The approximation with the Lorenz curve is calculated by fitting the periphery of the peak with the Lorenz curve for each peak of the spectrum, for example.
  • the present disclosure may adopt an embodiment in which the kurtosis of the spectrum is observed and the increase / decrease tendency of the microbend is detected by the magnitude of the kurtosis by utilizing the increase in the kurtosis.
  • the kurtosis of the spectrum can be calculated by the following formula.
  • the sample size is n
  • the mean value of each data xi is x
  • the sample standard deviation is s.
  • FIG. 4 shows an example of changes over time in GAWBS.
  • Each frequency is a frequency in which a peak exists in the spectrum of GAWBS.
  • the half width of the peak in the 108 MHz band at the start of the immersion test in which no microbend is generated is 0.768 MHz, which is 13.36 hours after the start of the immersion test in which the loss due to the microbend is increasing.
  • the half width of the peak is 0.366 MHz.
  • the half width of the peak at 270.16 hours after the start of the immersion test in which the loss due to microbend is reduced is 0.278 MHz. After the occurrence of microbend, the transmission loss increases and then gradually decreases.
  • the half-value width of the peak of the GAWBS spectrum is narrow, and it can be seen that the transmission loss tends to increase or decrease by using the half-value width.
  • the transmission loss tends to increase or decrease by using the half-value width.
  • the half width of GAWBS is 0.315 MHz, it can be seen that the transmission loss will decrease in the future. In this way, by using the change in the waveform of the GAWBS spectrum, it is possible to detect the tendency of increase / decrease in the microbend loss.
  • GAWBS includes polarized GAWBS and depolarized GAWBS, but either of them may be used.
  • the low frequency peak also has a GAWBS between the coating and the external environment.
  • the GAWBS between the coating and the external environment is small. Therefore, it is desirable to have a high frequency peak with a small amount of GAWBS between the coating and the external environment among the plurality of peaks.
  • the GAWBS spectrum can be measured by using a Fourier transform of the waveform of a spectrum analyzer or oscilloscope. Further, the Brillouen gain spectrum may be used for the measurement of the spectrum of GAWBS. Further, in the measurement of the spectrum of GAWBS, the frequency band in which the peak appears may be cut out by a filter. This speeds up signal processing. Further, it is desirable that the spectrum is subjected to additive averaging processing in order to reduce measurement noise.
  • (First Embodiment) 5 to 7 show an example of a system configuration according to the present disclosure.
  • the microbend loss increase / decrease tendency detecting device 10 according to the present disclosure is arranged in the base station 91 and connected to the optical fiber 95 to be measured.
  • both ends of the optical fiber 95 to be measured are connected to the microbend loss increase / decrease tendency detecting device 10.
  • one end of the optical fiber 95 to be measured is connected to the microbend loss increase / decrease tendency detecting device 10.
  • the microbend loss increase / decrease tendency detection device 10 includes a light source 11, a detector 12, and an analyzer / display 13, and measures the spectrum of GAWBS.
  • the light source 11 emits the test light to the optical fiber 95 to be measured.
  • the wavelength of the test light is arbitrary.
  • the wavelength of 1650 nm which is the test wavelength of the actual network, is used as the wavelength of the test light.
  • the detector 12 detects the scattered light in which the test light is scattered by the optical fiber 95 to be measured through the polarizing element.
  • the analyzer 13 measures GAWBS using the scattered light detected by the detector 12.
  • the analyzer 13 detects the tendency of increase / decrease in the microbend loss of the optical fiber 95 to be measured by using the spectrum.
  • the intensity of the line width of the GAWBS spectrum and the frequency intensity of the peak of the GAWBS spectrum are used to determine the increasing / decreasing tendency of the microbend loss.
  • the analyzer 13 in the microbend loss increase / decrease tendency detection device 10 of the present disclosure can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided through a network.
  • a coupler 14 is provided in the microbend loss increase / decrease tendency detecting device 10 in order to form a Sagnac loop.
  • the present disclosure can adopt a general polarized GAWBS measurement system.
  • the microbend loss increase / decrease tendency detecting device 10 includes a circulator 15.
  • the circulator 15 incidents the light from the light source 11 on the optical fiber 95 to be measured, and emits the scattered light from the optical fiber 95 to the detector 12.
  • the scattered light scattered by the optical fiber 95 to be measured is detected through the polarizing element.
  • the result shown in Fig. 3 can be obtained at each point in the longitudinal direction of the cable.
  • the threshold value By comparing the obtained results at each of these points with the threshold value, it is possible to specify the point where the increase / decrease tendency of the microbend loss is detected and to specify the distance from the microbend loss increase / decrease tendency detection device 10.
  • By using a database that manages the distance from the microbend loss increase / decrease tendency detection device 10 to each cable and the installation location of each cable it is possible to specify the installation location of the cable that has detected the microbend loss increase / decrease tendency.
  • FIG. 8 shows an example of the microbend loss increase / decrease tendency detection method of the present embodiment.
  • the microbend detection method of the present embodiment includes a GAWBS measurement procedure S101, a line width calculation procedure S102, a threshold value comparison procedure S103, a microbend loss increase tendency detection procedure S104, and a microbend loss decrease tendency detection procedure S105.
  • the light source 11, the detector 12, and the analyzer / display 13 measure the GAWBS.
  • the analyzer 13 calculates the line width of the GAWBS spectrum.
  • the threshold value comparison procedure S103 the line width of the GAWBS spectrum is compared with a predetermined threshold value. When the line width of the GAWBS spectrum is equal to or larger than a predetermined threshold value, the analyzer 13 determines that the microbend loss tends to increase in the optical fiber 95 to be measured (S104). When the line width of the GAWBS spectrum is less than a predetermined threshold value, the analyzer 13 determines that the microbend loss tends to decrease in the optical fiber 95 to be measured (S105).
  • the analyzer 13 indicates that the microbend loss of the optical fiber 95 to be measured is in an increasing tendency.
  • the analyzer 13 indicates that the microbend loss of the optical fiber 95 to be measured is in a decreasing tendency. At this time, the analyzer 13 may send an alarm to a predetermined address.
  • the line width calculation procedure S102 may be a procedure for calculating the intensity of the frequency of the peak, or may be a procedure for calculating the kurtosis of the spectrum.
  • the threshold value comparison procedure S103 when the threshold value is equal to or less than the predetermined threshold value, the analyzer 13 determines that the microbend loss tends to increase in the optical fiber 95 to be measured (S104). When the threshold value is equal to or higher than the predetermined threshold value, the analyzer 13 determines that the microbend loss tends to decrease in the optical fiber 95 to be measured (S105).
  • the microbend loss increase / decrease tendency detecting device 10 of the present embodiment can detect the increase / decrease tendency of the microbend loss of the optical fiber 95 to be measured in which microbend is generated.
  • the present disclosure can determine whether the microbend loss of the optical fiber under test will affect the service in the future. Further, it is considered that it is possible to cope with the generation of microbends due to, for example, high temperature and high humidity, other than the generation of microbends due to immersion.
  • (Second embodiment) 9 to 11 show an example of a system configuration according to the present disclosure.
  • the OTDR 51 outputs the pulsed light to the optical fiber 95 to be measured and outputs the return light from the optical fiber 95 to be measured.
  • the return light from the OTDR 51 may be converted from the modulation by GAWBS to the intensity modulation of the light by the polarizing element, or the SSB (single side-band) modulator may be used to convert the modulation by the return light.
  • the light of the light source may be interfered with and the modulation by GAWBS may be converted into the intensity modulation of the light.
  • the distance distribution of the GAWBS spectrum can be measured by measuring the signal received by the detector 12 on the analyzer 13 with an oscilloscope and measuring at each frequency while sweeping the frequency with an arbitrary waveform generator. Is.
  • the distance distribution of GAWBS can be measured by BOTDR (Brillouin Optical Time Domain Reflectometer).
  • the BOTDR 52 outputs pulsed light to the optical fiber 95 to be measured, and outputs a spectrum of Brillouin scattering measured from the return light of Brillouin scattering modulated by GAWBS from the optical fiber 95 to be measured.
  • the GAWBS spectrum is measured by subtracting the peak frequency (Brillouin frequency shift amount) of the Brillouin scattering spectrum from the Brillouin scattering spectrum measured by the BOTDR 52 on the analyzer 13.
  • the distance distribution of GAWBS can be measured by BOTDA (Brillouin Optical Time Domestic Analysis).
  • the BOTDA 53 outputs pulsed light and continuous light to the measured optical fiber 95, and outputs a Brillouin scattering spectrum obtained by measuring the gain or loss of the GAWBS-modulated Brillouin scattered light from the measured optical fiber 95.
  • the GAWBS spectrum is measured by subtracting the peak frequency (Brillouin frequency shift amount) of the Brillouin scattering spectrum from the Brillouin scattering spectrum measured by the BOTDA 53 on the analyzer 13.
  • FIG. 12 shows a first example of the microbend increase / decrease tendency detection method of the present embodiment.
  • the microbend increase / decrease tendency detection method of the present embodiment includes a temperature measurement procedure S111 before the GAWBS measurement procedure S101, and a temperature correction procedure S112 between the line width calculation procedure S102 and the threshold value comparison procedure S103.
  • BOTDR or ROTDR (Raman Optical Time Domain. Reflectory) measures Brillouin scattering or Raman scattering in the optical fiber 95 to be measured as in the form of FIG. 10, and the analyzer 13 measures the Brillouin scattering spectrum or the Brillouin scattering spectrum.
  • the distance distribution of the temperature in the optical fiber 95 to be measured is measured using the Raman scattering spectrum.
  • BOTDA measures the gain or loss due to Brillouin scattering in the measured optical fiber 95
  • the analyzer 13 uses the Brillouin scattering spectrum to measure the temperature distance distribution in the measured optical fiber 95. May be measured.
  • the analyzer 13 corrects the line width calculated in the line width calculation procedure S102 by using the temperature of the optical fiber 95 to be measured.
  • FIG. 13 shows a second example of the microbend increase / decrease tendency detection method of the present embodiment.
  • the microbend increase / decrease tendency detection method of the present embodiment includes a stress measurement procedure S121 before the GAWBS measurement procedure S101, and a stress correction procedure S122 between the line width calculation procedure S102 and the threshold value comparison procedure S103.
  • the BOTDR 52 measures the Brillouin scattering in the optical fiber 95 to be measured as shown in the form of FIG. 10, and the analyzer 13 uses the Brillouin scattering spectrum to measure the distance of the stress in the optical fiber 95 to be measured. Measure the distribution.
  • the BOTDA 53 measures the gain or loss due to Brillouin scattering in the measured optical fiber 95, and the analyzer 13 uses the Brillouin scattering spectrum to measure the stress distance distribution in the measured optical fiber 95. May be measured.
  • the analyzer 13 corrects the line width calculated in the line width calculation procedure S102 by using the stress in the optical fiber 95 to be measured.
  • FIG. 14 shows a third example of the microbend increase / decrease tendency detection method of the present embodiment.
  • the microbend increase / decrease tendency detection method of the present embodiment includes a temperature and stress measurement procedure S131 before the GAWBS measurement procedure S101, and a temperature and stress correction procedure S132 between the line width calculation procedure S102 and the threshold value comparison procedure S103.
  • the BOTDR 52 measures the Brillouin scattering in the measured optical fiber 95 as shown in the form of FIG. 10, and the analyzer 13 uses the Brillouin scattering spectrum to measure the stress in the measured optical fiber 95. Measure the distance distribution of.
  • the BOTDA 53 measures the gain or loss due to Brillouin scattering in the measured optical fiber 95
  • the analyzer 13 uses the Brillouin scattering spectrum to measure the distance distribution of stress in the measured optical fiber 95. May be measured.
  • the ROTDR measures the Raman scattering in the measured optical fiber 95
  • the analyzer 13 measures the temperature distance distribution in the measured optical fiber 95 using the Raman scattering spectrum. ..
  • the analyzer 13 corrects the line width calculated in the line width calculation procedure S102 using the temperature and stress of the optical fiber 95 to be measured.
  • the line width and kurtosis of GAWBS have a linear relationship with the acoustic impedance of the coating, and the acoustic impedance changes linearly with temperature and stress. Further, the strength of GAWBS changes as the line width changes. That is, GAWBS has a linear relationship with temperature and stress. Therefore, the analyzer 13 can detect the temperature change and the stress change by using the measured temperature and stress distance distribution, and can correct the GAWBS.
  • the present embodiment shows an example in which the line width calculation procedure S102 using the line width of the spectrum is executed and the line width is corrected, it can be applied to an arbitrary detection method using the spectrum and its correction.
  • the line width calculation procedure S102 may be a procedure for calculating the intensity of the peak frequency.
  • the intensity of the peak frequency is corrected in steps S112, S122, and S132.
  • This disclosure can be applied to the information and communication industry.
  • Microbend loss increase / decrease tendency detection device 11 Light source 12: Detector 13: Analysis / display 14: Coupler 15: Circulators 21, 22, 23: Closure 51: OTDR 52: BOTDR 53: BOTDA 91: Base stations 92, 93, 94: Manhole 95: Optical fiber to be measured

Abstract

The purpose of this disclosure is to detect the trend of the increase and decrease of microbending loss in an optical fiber in which microbending has occurred without requiring data about variation over time.　Disclosed is a device that measures the forward Brillouin scattering of an optical fiber under measurement in which microbending has occurred and detects the trend of the increase and decrease of microbending loss in the optical fiber under measurement on the basis of a characteristic of the vicinity of the peak of the forward Brillouin scattering.

Description

光ファイバのマイクロベンド損失の増減傾向を検知する装置及び方法Devices and methods for detecting the increasing / decreasing tendency of microbend loss of optical fibers
　光ファイバの保守運用に関する。 Regarding maintenance and operation of optical fiber.
　光ファイバの被覆に水が浸透するとマイクロベンドが発生する場合がある。光ファイバを保守する上で、特に浸漬によるマイクロベンド損失の増加は徐々に変化するため、光ファイバの保守において重要である。マイクロベンドによる損失を検知する方法として、ＯＴＤＲ（Ｏｐｔｉｃａｌ　Ｔｉｍｅ　Ｄｏｍａｉｎ　Ｒｅｆｌｅｃｔｏｍｅｔｅｒ）を用いた伝送損失や光パワーメータを用いた光損失を測定する方式がある。 Microbend may occur when water permeates the coating of the optical fiber. In the maintenance of the optical fiber, the increase in the microbend loss due to immersion changes gradually, which is important in the maintenance of the optical fiber. As a method of detecting a loss due to a microbend, there is a method of measuring a transmission loss using an OTDR (Optical Time Domain Reflectometer) or a light loss using an optical power meter.
　しかしながら、マイクロベンド損失は一度増加した後に減少する傾向を示すことが有り、損失を用いた検知では損失の経時変化のデータが無ければ、損失測定時にマイクロベンド損失の増減の傾向を知ることができない。このため、損失を用いた検知のみでは光ファイバの伝送損失が減少傾向にあり、伝送損失の観点からはサービス運用に問題が無い光ファイバの故障修理稼働が発生する場合がある。 However, the microbend loss may show a tendency to increase once and then decrease, and if there is no data on the change over time of the loss in the detection using the loss, it is not possible to know the tendency of the increase or decrease in the microbend loss at the time of loss measurement. .. Therefore, the transmission loss of the optical fiber tends to decrease only by the detection using the loss, and from the viewpoint of the transmission loss, the failure repair operation of the optical fiber without any problem in the service operation may occur.
　そこで、本開示は、不要な光ファイバの故障修理稼働の削減のために、経時変化のデータが不要な、マイクロベンドが発生している光ファイバのマイクロベンド損失の増減傾向を検知することを目的とする。 Therefore, the purpose of this disclosure is to detect an increase / decrease tendency of the microbend loss of an optical fiber in which microbend is generated, which does not require data on changes over time in order to reduce unnecessary repair operation of the optical fiber. And.
　本開示に係る装置は、
　対象とするマイクロベンドが発生している被測定光ファイバの前方ブリルアン散乱（ＧＡＷＢＳ）を測定し、
　前記前方ブリルアン散乱のピーク周辺の特性に基づいて、前記被測定光ファイバのマイクロベンド損失の増減傾向を検知する。 The device according to this disclosure is
Measure the forward Brillouin scattering (GAWBS) of the optical fiber to be measured in which the target microbend is generated, and measure it.
Based on the characteristics around the peak of the forward Brillouin scattering, the tendency of increase / decrease in the microbend loss of the optical fiber to be measured is detected.
　本開示に係る方法は、
　対象とするマイクロベンドが発生している被測定光ファイバの前方ブリルアン散乱を測定し、
　前記前方ブリルアン散乱のピーク周辺の特性に基づいて、前記被測定光ファイバのマイクロベンド損失の増減傾向を検知する。 The method pertaining to this disclosure is
Measure the forward Brillouin scattering of the optical fiber under test where the target microbend is generated,
Based on the characteristics around the peak of the forward Brillouin scattering, the tendency of increase / decrease in the microbend loss of the optical fiber to be measured is detected.
　本開示は、経時変化のデータが無い場合においても、その場でマイクロベンドが発生した光ファイバのマイクロベンド損失の増減傾向を検知することができる。これにより、マイクロベンド損失による光ファイバを用いた不要な故障修理稼働を減らすことができる。 This disclosure can detect an increase / decrease tendency of the microbend loss of an optical fiber in which microbend occurs on the spot even when there is no data of change with time. This makes it possible to reduce unnecessary failure repair operations using optical fibers due to microbend loss.
ＧＡＷＢＳの一例であり、（ａ）はデポラライズドＧＡＷＢＳ示し、（ｂ）はポラライズドＧＡＷＢＳを示す。As an example of GAWBS, (a) shows depolarized GAWBS and (b) shows polarized GAWBS. ＧＡＷＢＳのスペクトル波形の一例を示す。An example of the spectral waveform of GAWBS is shown. ＧＡＷＢＳのスペクトル波形のうちのピークの１つの拡大図を示す。An enlarged view of one of the peaks in the spectral waveform of GAWBS is shown. ＧＡＷＢＳの経時変化の一例を示す。An example of the change over time of GAWBS is shown. 第１の実施形態における第１のシステム構成例を示す。An example of the first system configuration in the first embodiment is shown. 第１の実施形態における第２のシステム構成例を示す。A second system configuration example in the first embodiment is shown. 第１の実施形態における第３のシステム構成例を示す。A third system configuration example in the first embodiment is shown. 第１の実施形態に係るマイクロベンド損失増減傾向検知方法の一例を示す。An example of the microbend loss increase / decrease tendency detection method according to the first embodiment is shown. 第２の実施形態における第１のシステム構成例を示す。An example of the first system configuration in the second embodiment is shown. 第２の実施形態における第２のシステム構成例を示す。A second system configuration example in the second embodiment is shown. 第２の実施形態における第３のシステム構成例を示す。A third system configuration example in the second embodiment is shown. 第２の実施形態のマイクロベンド損失増減傾向検知方法の第１例を示す。The first example of the microbend loss increase / decrease tendency detection method of 2nd Embodiment is shown. 第２の実施形態のマイクロベンド損失増減傾向検知方法の第２例を示す。A second example of the microbend loss increase / decrease tendency detection method of the second embodiment is shown. 第２の実施形態のマイクロベンド損失増減傾向検知方法の第３例を示す。A third example of the microbend loss increase / decrease tendency detection method of the second embodiment is shown.
　以下、本開示の実施形態について、図面を参照しながら詳細に説明する。なお、本開示は、以下に示す実施形態に限定されるものではない。これらの実施の例は例示に過ぎず、本開示は当業者の知識に基づいて種々の変更、改良を施した形態で実施することができる。なお、本明細書及び図面において符号が同じ構成要素は、相互に同一のものを示すものとする。 Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The present disclosure is not limited to the embodiments shown below. Examples of these implementations are merely examples, and the present disclosure can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. In the present specification and the drawings, the components having the same reference numerals indicate the same components.
＜原理＞
　図１に、ＧＡＷＢＳ（Ｇｕｉｄｅｄ　ａｃｏｕｓｔｉｃ－ｗａｖｅ　Ｂｒｉｌｌｏｕｉｎ　ｓｃａｔｔｅｒｉｎｇ）の一例を示す。光ファイバでは、光ファイバに光が入射されると、光ファイバのコア部分の光吸収で熱が発生し、これに伴い音波が発生する。ＧＡＷＢＳは、光ファイバの半径方向に反射しながら伝播する音波により、光ファイバ内を伝播する光の偏波及び位相が変調される現象である。ＧＡＷＢＳのスペクトルは音波の伝播損失に依存し、その主要因は音波の反射率である。光ファイバ内での音波の反射率は、光ファイバ外部の音響インピーダンスの影響を受ける。光ファイバの音響インピーダンスは、光ファイバの被覆の変化に応じて変化する。 <Principle>
FIG. 1 shows an example of GAWBS (Guided acoustic-wave Brillouin scattering). In an optical fiber, when light is incident on the optical fiber, heat is generated by light absorption of the core portion of the optical fiber, and sound waves are generated accordingly. GAWBS is a phenomenon in which the polarization and phase of light propagating in an optical fiber are modulated by sound waves propagating while reflecting in the radial direction of the optical fiber. The spectrum of GAWBS depends on the propagation loss of the sound wave, the main factor of which is the reflectance of the sound wave. The reflectance of sound waves inside an optical fiber is affected by the acoustic impedance outside the optical fiber. The acoustic impedance of an optical fiber changes in response to changes in the coating of the optical fiber.
　マイクロベンドが発生している光ファイバの被覆の状態が変化し、被覆の変化に伴い、音響インピーダンスも変化し、ＧＡＷＢＳのスペクトルが変化すると考えられる。例えば光ファイバ外部の音響インピーダンスが下がり、光ファイバ内での音波の反射率が上がるとＧＡＷＢＳスペクトルのピークの半値幅は減少する。本開示は、その変化を用いて、マイクロベンドが発生している光ファイバのマイクロベンド損失の増減傾向を検知する。 It is considered that the state of the coating of the optical fiber in which microbend is generated changes, and the acoustic impedance also changes with the change of the coating, and the spectrum of GAWBS changes. For example, when the acoustic impedance outside the optical fiber decreases and the reflectance of the sound wave inside the optical fiber increases, the half-value width of the peak of the GAWBS spectrum decreases. The present disclosure uses the change to detect an increasing / decreasing tendency of the microbend loss of the optical fiber in which microbend is generated.
　図２に、ＧＡＷＢＳのスペクトル波形の一例を示す。図３に、ＧＡＷＢＳのスペクトル波形のうちのピークの１つの拡大図を示す。マイクロベンドの発生によって伝送損失が大きくなるに従い、スペクトルが変化することが分かる。そこで、本開示は、以下に示すような前方ブリルアン散乱（ＧＡＷＢＳ）のスペクトルの変化の任意の組み合わせを用いて、光ファイバの被覆の状態変化を検知する。 FIG. 2 shows an example of the spectral waveform of GAWBS. FIG. 3 shows an enlarged view of one of the peaks in the spectral waveform of GAWBS. It can be seen that the spectrum changes as the transmission loss increases due to the generation of microbends. Therefore, the present disclosure uses any combination of spectral changes in forward Brillouin scattering (GAWBS) as shown below to detect changes in the state of the optical fiber coating.
　－ピークの周波数の強度
　図３に示すように、マイクロベンド損失は一度増加した後に減少しているが、ＧＡＷＢＳのスペクトルのピークの周波数の強度はマイクロベンド損失が減少傾向に転じた後も大きくなる。本開示は、ＧＡＷＢＳのスペクトルのピークの周波数の強度を観測し、当該強度がマイクロベンド損失の減少後も大きくなることを利用して、当該強度の大きさにてマイクロベンド損失の増減傾向を検知する態様を採用しうる。 -Peak frequency intensity As shown in FIG. 3, the microbend loss increases once and then decreases, but the peak frequency intensity of the GAWBS spectrum increases even after the microbend loss starts to decrease. .. In the present disclosure, the intensity of the frequency of the peak of the spectrum of GAWBS is observed, and the increase / decrease tendency of the microbend loss is detected by the magnitude of the intensity by utilizing the fact that the intensity increases even after the decrease of the microbend loss. Aspects can be adopted.
　－ＧＡＷＢＳのスペクトルの線幅
　図３に示すように、マイクロベンド損失は一度増加した後に減少しているが、ＧＡＷＢＳのスペクトルの線幅はマイクロベンド損失が減少傾向に転じた後も狭くなる。本開示は、ＧＡＷＢＳのスペクトル線幅が狭くなることを利用して、当該線幅の狭さにてマイクロベンド損失の増減傾向を検知する態様を採用しうる。線幅は、スペクトルをローレンツ曲線で近似することで、算出することができる。ローレンツ曲線での近似は、例えば、スペクトルのピーク毎にピーク周辺をローレンツ曲線でフィッティングして算出する。 -GAWBS spectral line width As shown in FIG. 3, the microbend loss increases once and then decreases, but the GAWBS spectral line width narrows even after the microbend loss starts to decrease. In the present disclosure, it is possible to adopt an embodiment in which the tendency of increase / decrease of the microbend loss is detected by the narrowness of the spectral line width of the GAWBS by utilizing the narrowing of the spectral line width of the GAWBS. The line width can be calculated by approximating the spectrum with a Lorenz curve. The approximation with the Lorenz curve is calculated by fitting the periphery of the peak with the Lorenz curve for each peak of the spectrum, for example.
　－ＧＡＷＢＳのスペクトルの尖度
　図３に示すように、スペクトルの線幅が狭くなると共に、スペクトルの尖度が増加する。尖度は正規分布よりどれだけ尖っているかである。そのため、本開示は、スペクトルの尖度を観測し、当該尖度が増加することを利用して、当該尖度の大きさにてマイクロベンドの増減傾向を検知する態様を採用しうる。例えば、スペクトルの尖度は、下記の式で算出することができる。ここで、サンプルサイズをｎ、各データｘｉ（ｉ：１，２，…，ｎ）の平均値をｘ、標本標準偏差をｓとする。
Figure JPOXMLDOC01-appb-M000001
 -GAWBS spectral kurtosis As shown in FIG. 3, the spectral line width becomes narrower and the spectral kurtosis increases. Kurtosis is how sharp the distribution is. Therefore, the present disclosure may adopt an embodiment in which the kurtosis of the spectrum is observed and the increase / decrease tendency of the microbend is detected by the magnitude of the kurtosis by utilizing the increase in the kurtosis. For example, the kurtosis of the spectrum can be calculated by the following formula. Here, the sample size is n, the mean value of each data xi (i: 1, 2, ..., N) is x, and the sample standard deviation is s.
Figure JPOXMLDOC01-appb-M000001
　図４に、ＧＡＷＢＳの経時変化の一例を示す。各周波数は、ＧＡＷＢＳのスペクトルにおいてピークの存在する周波数である。マイクロベンドが発生していない浸漬試験開始時点での１０８ＭＨｚ帯のピークの半値幅は、０．７６８ＭＨｚであり、マイクロベンドによる損失が増加している浸漬試験開始から１３．３６時間後の時点でのピークの半値幅は、０．３６６ＭＨｚである。これに対して、マイクロベンドによる損失が減少している浸漬試験開始から２７０．１６時間後の時点でのピークの半値幅は、０．２７８ＭＨｚである。マイクロベンドの発生後、伝送損失は増加し、その後、緩やかに減少する。一方で、ＧＡＷＢＳのスペクトルのピークの半値幅は狭くなっており、半値幅を用いることで伝送損失の増減傾向が分かる。例えば、図４に示す光ファイバの場合には、ＯＴＤＲでの計測結果が伝送損失０．５２２ｄＢ／ｋｍで、ＧＡＷＢＳの半値幅が０．３９５ＭＨｚの場合には伝送損失は今後、伝送損失は増加することが分かる。一方で、ＧＡＷＢＳの半値幅が０．３１５ＭＨｚの場合には今後、伝送損失は減少することが分かる。このように、ＧＡＷＢＳのスペクトルの波形の変化を用いることで、マイクロベンド損失の増減傾向を検知することができる。 FIG. 4 shows an example of changes over time in GAWBS. Each frequency is a frequency in which a peak exists in the spectrum of GAWBS. The half width of the peak in the 108 MHz band at the start of the immersion test in which no microbend is generated is 0.768 MHz, which is 13.36 hours after the start of the immersion test in which the loss due to the microbend is increasing. The half width of the peak is 0.366 MHz. On the other hand, the half width of the peak at 270.16 hours after the start of the immersion test in which the loss due to microbend is reduced is 0.278 MHz. After the occurrence of microbend, the transmission loss increases and then gradually decreases. On the other hand, the half-value width of the peak of the GAWBS spectrum is narrow, and it can be seen that the transmission loss tends to increase or decrease by using the half-value width. For example, in the case of the optical fiber shown in FIG. 4, when the measurement result by OTDR is a transmission loss of 0.522 dB / km and the half width of GAWBS is 0.395 MHz, the transmission loss will increase in the future. You can see that. On the other hand, when the half width of GAWBS is 0.315 MHz, it can be seen that the transmission loss will decrease in the future. In this way, by using the change in the waveform of the GAWBS spectrum, it is possible to detect the tendency of increase / decrease in the microbend loss.
＜測定方法＞
　マイクロベンドによるＧＡＷＢＳのスペクトルの変化は偏光の有無に依らず発生する。そのため、ＧＡＷＢＳにはポラライズドＧＡＷＢＳとデポラライズドＧＡＷＢＳがあるが、どちらを使用してもよい <Measurement method>
The change in the spectrum of GAWBS due to microbend occurs with or without polarization. Therefore, GAWBS includes polarized GAWBS and depolarized GAWBS, but either of them may be used.
　また、ＧＡＷＢＳのスペクトルのピークは複数存在するが、どのピークを用いても良い。ただし、複数のピークのうちの低周波のピークには被覆と外部環境とのＧＡＷＢＳもある。マイクロベンド損失の検出効率を上げるためには、被覆と外部環境とのＧＡＷＢＳは少ない方が好ましい。そのため、複数のピークのうちの被覆と外部環境とのＧＡＷＢＳの少ない、ある程度高周波のピークが望ましい。一方で、強度が最大のピークを用いるなど、スペクトルのピークでの強度が大きい周波数を用いて判定することが望ましい。 Although there are multiple peaks in the spectrum of GAWBS, any peak may be used. However, among the plurality of peaks, the low frequency peak also has a GAWBS between the coating and the external environment. In order to improve the detection efficiency of microbend loss, it is preferable that the GAWBS between the coating and the external environment is small. Therefore, it is desirable to have a high frequency peak with a small amount of GAWBS between the coating and the external environment among the plurality of peaks. On the other hand, it is desirable to use a frequency with a high intensity at the peak of the spectrum, such as using the peak with the maximum intensity.
　ＧＡＷＢＳのスペクトルの測定は、スペクトラムアナライザやオシロスコープの波形のフーリエ変換を用いることができる。また、ＧＡＷＢＳのスペクトルの測定は、ブリルアン利得スペクトルを利用しても良い。また、ＧＡＷＢＳのスペクトルの測定は、ピークの出現する周波数帯をフィルタにて切り出しても良い。これにより、信号処理が早くなる。また、スペクトルは、測定ノイズを減少させるために加算平均処理を行うことが望ましい。 The GAWBS spectrum can be measured by using a Fourier transform of the waveform of a spectrum analyzer or oscilloscope. Further, the Brillouen gain spectrum may be used for the measurement of the spectrum of GAWBS. Further, in the measurement of the spectrum of GAWBS, the frequency band in which the peak appears may be cut out by a filter. This speeds up signal processing. Further, it is desirable that the spectrum is subjected to additive averaging processing in order to reduce measurement noise.
（第１の実施形態）
　図５～図７に、本開示に係るシステム構成例を示す。本開示に係るマイクロベンド損失増減傾向検知装置１０は、基地局９１内に配置され、被測定光ファイバ９５に接続される。図５に示す第１のシステム構成例及び図６に示す第２のシステム構成例は、被測定光ファイバ９５の両端がマイクロベンド損失増減傾向検知装置１０に接続されている。図７に示す第３のシステム構成例は、被測定光ファイバ９５の片端がマイクロベンド損失増減傾向検知装置１０に接続されている。 (First Embodiment)
5 to 7 show an example of a system configuration according to the present disclosure. The microbend loss increase / decrease tendency detecting device 10 according to the present disclosure is arranged in the base station 91 and connected to the optical fiber 95 to be measured. In the first system configuration example shown in FIG. 5 and the second system configuration example shown in FIG. 6, both ends of the optical fiber 95 to be measured are connected to the microbend loss increase / decrease tendency detecting device 10. In the third system configuration example shown in FIG. 7, one end of the optical fiber 95 to be measured is connected to the microbend loss increase / decrease tendency detecting device 10.
　マイクロベンド損失増減傾向検知装置１０は、光源１１、検出器１２及び分析・表示器１３を備え、ＧＡＷＢＳのスペクトルを測定する。光源１１は、試験光を被測定光ファイバ９５に出射する。試験光の波長は任意である。被測定光ファイバ９５に現用回線を用いる場合には、実網の試験波長である１６５０ｎｍの波長を試験光の波長に用いる。検出器１２は、偏光子を通して、試験光が被測定光ファイバ９５で散乱された散乱光を検出する。分析・表示器１３は、検出器１２の検出した散乱光を用いて、ＧＡＷＢＳを測定する。そして、分析・表示器１３は、スペクトルを用いて、被測定光ファイバ９５のマイクロベンド損失の増減傾向を検知する。マイクロベンド損失の増減傾向の判定は、原理において説明したとおり、ＧＡＷＢＳのスペクトルの線幅やＧＡＷＢＳのスペクトルのピークの周波数の強度を用いる。 The microbend loss increase / decrease tendency detection device 10 includes a light source 11, a detector 12, and an analyzer / display 13, and measures the spectrum of GAWBS. The light source 11 emits the test light to the optical fiber 95 to be measured. The wavelength of the test light is arbitrary. When a working line is used for the optical fiber 95 to be measured, the wavelength of 1650 nm, which is the test wavelength of the actual network, is used as the wavelength of the test light. The detector 12 detects the scattered light in which the test light is scattered by the optical fiber 95 to be measured through the polarizing element. The analyzer 13 measures GAWBS using the scattered light detected by the detector 12. Then, the analyzer 13 detects the tendency of increase / decrease in the microbend loss of the optical fiber 95 to be measured by using the spectrum. As explained in principle, the intensity of the line width of the GAWBS spectrum and the frequency intensity of the peak of the GAWBS spectrum are used to determine the increasing / decreasing tendency of the microbend loss.
　本開示のマイクロベンド損失増減傾向検知装置１０における分析・表示器１３は、コンピュータとプログラムによっても実現でき、プログラムを記録媒体に記録することも、ネットワークを通して提供することも可能である。 The analyzer 13 in the microbend loss increase / decrease tendency detection device 10 of the present disclosure can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided through a network.
　図６に示す第２のシステム構成例では、サニャックループを組むために、マイクロベンド損失増減傾向検知装置１０にカプラ１４が備わっている。図６に示すように、本開示は、一般的なポラライズドＧＡＷＢＳの測定系を採用することができる。 In the second system configuration example shown in FIG. 6, a coupler 14 is provided in the microbend loss increase / decrease tendency detecting device 10 in order to form a Sagnac loop. As shown in FIG. 6, the present disclosure can adopt a general polarized GAWBS measurement system.
　図７に示す第３のシステム構成例では、マイクロベンド損失増減傾向検知装置１０がサーキュレータ１５を備える。サーキュレータ１５は、光源１１からの光を被測定光ファイバ９５に入射し、被測定光ファイバ９５での散乱光を検出器１２に出射する。被測定光ファイバ９５で散乱された散乱光は偏光子を通して検出する。 In the third system configuration example shown in FIG. 7, the microbend loss increase / decrease tendency detecting device 10 includes a circulator 15. The circulator 15 incidents the light from the light source 11 on the optical fiber 95 to be measured, and emits the scattered light from the optical fiber 95 to the detector 12. The scattered light scattered by the optical fiber 95 to be measured is detected through the polarizing element.
　距離分布の計測を行うと、図３のような結果が、ケーブルの長手方向の各地点で得られる。この各地点の得られた結果と閾値を比較することで、マイクロベンド損失の増減傾向を検知した地点を特定し、マイクロベンド損失増減傾向検知装置１０からの距離を特定することができる。マイクロベンド損失増減傾向検知装置１０から各ケーブルまでの距離や各ケーブルの設置場所を管理したデータベースを用いることで、マイクロベンド損失増減傾向を検知したケーブルの設置場所を特定することができる。 When the distance distribution is measured, the result shown in Fig. 3 can be obtained at each point in the longitudinal direction of the cable. By comparing the obtained results at each of these points with the threshold value, it is possible to specify the point where the increase / decrease tendency of the microbend loss is detected and to specify the distance from the microbend loss increase / decrease tendency detection device 10. By using a database that manages the distance from the microbend loss increase / decrease tendency detection device 10 to each cable and the installation location of each cable, it is possible to specify the installation location of the cable that has detected the microbend loss increase / decrease tendency.
　図８に、本実施形態のマイクロベンド損失増減傾向検知方法の一例を示す。本実施形態のマイクロベンド検知方法は、ＧＡＷＢＳ測定手順Ｓ１０１、線幅算出手順Ｓ１０２、閾値比較手順Ｓ１０３、マイクロベンド損失増加傾向検知手順Ｓ１０４、マイクロベンド損失減少傾向検知手順Ｓ１０５を備える。 FIG. 8 shows an example of the microbend loss increase / decrease tendency detection method of the present embodiment. The microbend detection method of the present embodiment includes a GAWBS measurement procedure S101, a line width calculation procedure S102, a threshold value comparison procedure S103, a microbend loss increase tendency detection procedure S104, and a microbend loss decrease tendency detection procedure S105.
　ＧＡＷＢＳ測定手順Ｓ１０１では、光源１１、検出器１２及び分析・表示器１３が、ＧＡＷＢＳを測定する。
　線幅算出手順Ｓ１０２では、分析・表示器１３が、ＧＡＷＢＳのスペクトルの線幅を算出する。
　閾値比較手順Ｓ１０３では、ＧＡＷＢＳのスペクトルの線幅を、予め定められた閾値と比較する。ＧＡＷＢＳのスペクトルの線幅が予め定められた閾値以上の場合、分析・表示器１３は、被測定光ファイバ９５にマイクロベンド損失が増加傾向にあると判定する（Ｓ１０４）。ＧＡＷＢＳのスペクトルの線幅が予め定められた閾値未満の場合、分析・表示器１３は、被測定光ファイバ９５にマイクロベンド損失が減少傾向にあると判定する（Ｓ１０５）。
　マイクロベンド損失増加傾向検知手順Ｓ１０４では、分析・表示器１３は、被測定光ファイバ９５のマイクロベンド損失が増加傾向の状態である旨を表示する。
　マイクロベンド損失減少傾向検知手順Ｓ１０５では、分析・表示器１３は、被測定光ファイバ９５のマイクロベンド損失が減少傾向の状態である旨を表示する。このとき、分析・表示器１３は、予め定められたアドレスにアラームを送信してもよい。 In the GAWBS measurement procedure S101, the light source 11, the detector 12, and the analyzer / display 13 measure the GAWBS.
In the line width calculation procedure S102, the analyzer 13 calculates the line width of the GAWBS spectrum.
In the threshold value comparison procedure S103, the line width of the GAWBS spectrum is compared with a predetermined threshold value. When the line width of the GAWBS spectrum is equal to or larger than a predetermined threshold value, the analyzer 13 determines that the microbend loss tends to increase in the optical fiber 95 to be measured (S104). When the line width of the GAWBS spectrum is less than a predetermined threshold value, the analyzer 13 determines that the microbend loss tends to decrease in the optical fiber 95 to be measured (S105).
In the microbend loss increasing tendency detection procedure S104, the analyzer 13 indicates that the microbend loss of the optical fiber 95 to be measured is in an increasing tendency.
In the microbend loss decreasing tendency detection procedure S105, the analyzer 13 indicates that the microbend loss of the optical fiber 95 to be measured is in a decreasing tendency. At this time, the analyzer 13 may send an alarm to a predetermined address.
　なお、本実施形態ではスペクトルの線幅を用いる線幅算出手順Ｓ１０２を実行する例を示したが、スペクトルを用いた任意の検知方法を用いることができる。例えば、線幅算出手順Ｓ１０２は、ピークの周波数の強度を算出する手順であってもよいし、スペクトルの尖度を算出する手順であってもよい。その場合、閾値比較手順Ｓ１０３では、予め定められた閾値以下の場合、分析・表示器１３は、被測定光ファイバ９５にマイクロベンド損失が増加傾向にあると判定する（Ｓ１０４）。予め定められた閾値以上の場合、分析・表示器１３は、被測定光ファイバ９５にマイクロベンド損失が減少傾向にあると判定する（Ｓ１０５）。 Although the example of executing the line width calculation procedure S102 using the line width of the spectrum is shown in the present embodiment, any detection method using the spectrum can be used. For example, the line width calculation procedure S102 may be a procedure for calculating the intensity of the frequency of the peak, or may be a procedure for calculating the kurtosis of the spectrum. In that case, in the threshold value comparison procedure S103, when the threshold value is equal to or less than the predetermined threshold value, the analyzer 13 determines that the microbend loss tends to increase in the optical fiber 95 to be measured (S104). When the threshold value is equal to or higher than the predetermined threshold value, the analyzer 13 determines that the microbend loss tends to decrease in the optical fiber 95 to be measured (S105).
　以上説明したように、本実施形態のマイクロベンド損失増減傾向検知装置１０は、マイクロベンドが発生している被測定光ファイバ９５のマイクロベンド損失の増減傾向を検知することができる。ここで、ＧＡＷＢＳのスペクトル波形の変化を用いることで、経時変化を測定することなく、伝送損失の増減傾向を検知することができる。そのため、本開示は、被測定光ファイバのマイクロベンド損失が今後、サービスに影響を与えるかどうかを判定できる。さらに、浸漬によるマイクロベンド発生以外であっても、例えば高温高湿によるマイクロベンド発生にも対応可能と考えられる。 As described above, the microbend loss increase / decrease tendency detecting device 10 of the present embodiment can detect the increase / decrease tendency of the microbend loss of the optical fiber 95 to be measured in which microbend is generated. Here, by using the change in the spectral waveform of GAWBS, it is possible to detect the tendency of increase / decrease in the transmission loss without measuring the change with time. Therefore, the present disclosure can determine whether the microbend loss of the optical fiber under test will affect the service in the future. Further, it is considered that it is possible to cope with the generation of microbends due to, for example, high temperature and high humidity, other than the generation of microbends due to immersion.
（第２の実施形態）
　図９～図１１に、本開示に係るシステム構成例を示す。図９の形態では、ＯＴＤＲ５１は、被測定光ファイバ９５にパルス化した光を出力し、被測定光ファイバ９５からの戻り光を出力する。検出器１２では、ＯＴＤＲ５１からの戻り光を、偏光子にてＧＡＷＢＳによる変調を光の強度変調に変換しても良いし、ＳＳＢ（ｓｉｎｇｌｅ　ｓｉｄｅ－ｂａｎｄ）変調器を用いて、戻り光と別の光源の光を干渉させ、ＧＡＷＢＳによる変調を光の強度変調に変換しても良い。ＳＳＢ変調器を用いる際の光源は光源による測定ノイズを低減するためにＯＴＤＲ５１を用いるのが望ましい。分析・表示器１３にて検出器１２で受光した信号をオシロスコープにて計測し、任意波形発生器にて周波数を掃引しながら各周波数にて計測することで、ＧＡＷＢＳスペクトルの距離分布の計測が可能である。 (Second embodiment)
9 to 11 show an example of a system configuration according to the present disclosure. In the embodiment of FIG. 9, the OTDR 51 outputs the pulsed light to the optical fiber 95 to be measured and outputs the return light from the optical fiber 95 to be measured. In the detector 12, the return light from the OTDR 51 may be converted from the modulation by GAWBS to the intensity modulation of the light by the polarizing element, or the SSB (single side-band) modulator may be used to convert the modulation by the return light. The light of the light source may be interfered with and the modulation by GAWBS may be converted into the intensity modulation of the light. When using the SSB modulator, it is desirable to use OTDR51 as the light source in order to reduce the measurement noise caused by the light source. The distance distribution of the GAWBS spectrum can be measured by measuring the signal received by the detector 12 on the analyzer 13 with an oscilloscope and measuring at each frequency while sweeping the frequency with an arbitrary waveform generator. Is.
　図１０の形態では、ＢＯＴＤＲ（Ｂｒｉｌｌｏｕｉｎ　Ｏｐｔｉｃａｌ　Ｔｉｍｅ　Ｄｏｍａｉｎ　Ｒｅｆｌｅｃｔｏｍｅｔｅｒ）にてＧＡＷＢＳの距離分布を計測することができる。ＢＯＴＤＲ５２は被測定光ファイバ９５にパルス化した光を出力し、被測定光ファイバ９５からのＧＡＷＢＳにより変調されたブリルアン散乱の戻り光から計測したブリルアン散乱のスペクトルを出力する。分析・表示器１３にてＢＯＴＤＲ５２にて計測したブリルアン散乱のスペクトルからブリルアン散乱のスペクトルのピーク周波数（ブリルアン周波数シフト量）を引くことでＧＡＷＢＳスペクトルを計測する。 In the form of FIG. 10, the distance distribution of GAWBS can be measured by BOTDR (Brillouin Optical Time Domain Reflectometer). The BOTDR 52 outputs pulsed light to the optical fiber 95 to be measured, and outputs a spectrum of Brillouin scattering measured from the return light of Brillouin scattering modulated by GAWBS from the optical fiber 95 to be measured. The GAWBS spectrum is measured by subtracting the peak frequency (Brillouin frequency shift amount) of the Brillouin scattering spectrum from the Brillouin scattering spectrum measured by the BOTDR 52 on the analyzer 13.
　図１１の形態では、ＢＯＴＤＡ（Ｂｒｉｌｌｏｕｉｎ　Ｏｐｔｉｃａｌ　Ｔｉｍｅ　Ｄｏｍａｉｎ　Ａｎａｌｙｓｉｓ）にてＧＡＷＢＳの距離分布を計測することができる。ＢＯＴＤＡ５３は被測定光ファイバ９５にパルス化した光と連続光を出力し、被測定光ファイバ９５からのＧＡＷＢＳにより変調されたブリルアン散乱光による利得あるいは損失を計測したブリルアン散乱のスペクトルを出力する。分析・表示器１３にてＢＯＴＤＡ５３にて計測したブリルアン散乱のスペクトルからブリルアン散乱のスペクトルのピーク周波数（ブリルアン周波数シフト量）を引くことでＧＡＷＢＳスペクトルを計測する。 In the form of FIG. 11, the distance distribution of GAWBS can be measured by BOTDA (Brillouin Optical Time Domestic Analysis). The BOTDA 53 outputs pulsed light and continuous light to the measured optical fiber 95, and outputs a Brillouin scattering spectrum obtained by measuring the gain or loss of the GAWBS-modulated Brillouin scattered light from the measured optical fiber 95. The GAWBS spectrum is measured by subtracting the peak frequency (Brillouin frequency shift amount) of the Brillouin scattering spectrum from the Brillouin scattering spectrum measured by the BOTDA 53 on the analyzer 13.
　図１２に、本実施形態のマイクロベンド増減傾向検知方法の第１例を示す。本実施形態のマイクロベンド増減傾向検知方法は、ＧＡＷＢＳ測定手順Ｓ１０１の前に温度測定手順Ｓ１１１を備え、線幅算出手順Ｓ１０２と閾値比較手順Ｓ１０３の間に温度補正手順Ｓ１１２を備える。 FIG. 12 shows a first example of the microbend increase / decrease tendency detection method of the present embodiment. The microbend increase / decrease tendency detection method of the present embodiment includes a temperature measurement procedure S111 before the GAWBS measurement procedure S101, and a temperature correction procedure S112 between the line width calculation procedure S102 and the threshold value comparison procedure S103.
　温度測定Ｓ１１１では、図１０の形態のようにＢＯＴＤＲあるいはＲＯＴＤＲ（Ｒａｍａｎ　Ｏｐｔｉｃａｌ　Ｔｉｍｅ　Ｄｏｍａｉｎ．　Ｒｅｆｌｅｃｔｏｍｅｔｒｙ）が被測定光ファイバ９５でのブリルアン散乱あるいはラマン散乱を測定し、分析・表示器１３がブリルアン散乱スペクトルあるいはラマン散乱スペクトルを用いて被測定光ファイバ９５での温度の距離分布を測定する。あるいは図１１の形態のようにＢＯＴＤＡが被測定光ファイバ９５でのブリルアン散乱による利得あるいは損失を測定し、分析・表示器１３がブリルアン散乱スペクトルを用いて被測定光ファイバ９５での温度の距離分布を測定しても良い。 In the temperature measurement S111, BOTDR or ROTDR (Raman Optical Time Domain. Reflectory) measures Brillouin scattering or Raman scattering in the optical fiber 95 to be measured as in the form of FIG. 10, and the analyzer 13 measures the Brillouin scattering spectrum or the Brillouin scattering spectrum. The distance distribution of the temperature in the optical fiber 95 to be measured is measured using the Raman scattering spectrum. Alternatively, as in the form of FIG. 11, BOTDA measures the gain or loss due to Brillouin scattering in the measured optical fiber 95, and the analyzer 13 uses the Brillouin scattering spectrum to measure the temperature distance distribution in the measured optical fiber 95. May be measured.
　温度補正手順Ｓ１１２では、分析・表示器１３が、被測定光ファイバ９５での温度を用いて、線幅算出手順Ｓ１０２で算出した線幅を補正する。 In the temperature correction procedure S112, the analyzer 13 corrects the line width calculated in the line width calculation procedure S102 by using the temperature of the optical fiber 95 to be measured.
　図１３に、本実施形態のマイクロベンド増減傾向検知方法の第２例を示す。本実施形態のマイクロベンド増減傾向検知方法は、ＧＡＷＢＳ測定手順Ｓ１０１の前に応力測定手順Ｓ１２１を備え、線幅算出手順Ｓ１０２と閾値比較手順Ｓ１０３の間に応力補正手順Ｓ１２２を備える。 FIG. 13 shows a second example of the microbend increase / decrease tendency detection method of the present embodiment. The microbend increase / decrease tendency detection method of the present embodiment includes a stress measurement procedure S121 before the GAWBS measurement procedure S101, and a stress correction procedure S122 between the line width calculation procedure S102 and the threshold value comparison procedure S103.
　応力測定手順Ｓ１２１では、図１０の形態のようにＢＯＴＤＲ５２が被測定光ファイバ９５でのブリルアン散乱を測定し、分析・表示器１３がブリルアン散乱スペクトルを用いて被測定光ファイバ９５での応力の距離分布を測定する。あるいは図１１の形態のようにＢＯＴＤＡ５３が被測定光ファイバ９５でのブリルアン散乱による利得あるいは損失を測定し、分析・表示器１３がブリルアン散乱スペクトルを用いて被測定光ファイバ９５での応力の距離分布を測定しても良い。
　応力補正手順Ｓ１２２では、分析・表示器１３が、被測定光ファイバ９５での応力を用いて、線幅算出手順Ｓ１０２で算出した線幅を補正する。 In the stress measurement procedure S121, the BOTDR 52 measures the Brillouin scattering in the optical fiber 95 to be measured as shown in the form of FIG. 10, and the analyzer 13 uses the Brillouin scattering spectrum to measure the distance of the stress in the optical fiber 95 to be measured. Measure the distribution. Alternatively, as in the form of FIG. 11, the BOTDA 53 measures the gain or loss due to Brillouin scattering in the measured optical fiber 95, and the analyzer 13 uses the Brillouin scattering spectrum to measure the stress distance distribution in the measured optical fiber 95. May be measured.
In the stress correction procedure S122, the analyzer 13 corrects the line width calculated in the line width calculation procedure S102 by using the stress in the optical fiber 95 to be measured.
　図１４に、本実施形態のマイクロベンド増減傾向検知方法の第３例を示す。本実施形態のマイクロベンド増減傾向検知方法は、ＧＡＷＢＳ測定手順Ｓ１０１の前に温度及び応力測定手順Ｓ１３１を備え、線幅算出手順Ｓ１０２と閾値比較手順Ｓ１０３の間に温度及び応力補正手順Ｓ１３２を備える。 FIG. 14 shows a third example of the microbend increase / decrease tendency detection method of the present embodiment. The microbend increase / decrease tendency detection method of the present embodiment includes a temperature and stress measurement procedure S131 before the GAWBS measurement procedure S101, and a temperature and stress correction procedure S132 between the line width calculation procedure S102 and the threshold value comparison procedure S103.
　温度及び応力測定手順Ｓ１３１では、図１０の形態のようにＢＯＴＤＲ５２が被測定光ファイバ９５でのブリルアン散乱を測定し、分析・表示器１３がブリルアン散乱スペクトルを用いて被測定光ファイバ９５での応力の距離分布を測定する。あるいは図１１の形態のようにＢＯＴＤＡ５３が被測定光ファイバ９５でのブリルアン散乱による利得あるいは損失を測定し、分析・表示器１３がブリルアン散乱スペクトルを用いて被測定光ファイバ９５での応力の距離分布を測定しても良い。また、図１０の形態のようにＲＯＴＤＲが被測定光ファイバ９５でのラマン散乱を測定し、分析・表示器１３がラマン散乱スペクトルを用いて被測定光ファイバ９５での温度の距離分布を測定する。 In the temperature and stress measurement procedure S131, the BOTDR 52 measures the Brillouin scattering in the measured optical fiber 95 as shown in the form of FIG. 10, and the analyzer 13 uses the Brillouin scattering spectrum to measure the stress in the measured optical fiber 95. Measure the distance distribution of. Alternatively, as in the form of FIG. 11, the BOTDA 53 measures the gain or loss due to Brillouin scattering in the measured optical fiber 95, and the analyzer 13 uses the Brillouin scattering spectrum to measure the distance distribution of stress in the measured optical fiber 95. May be measured. Further, as shown in the embodiment of FIG. 10, the ROTDR measures the Raman scattering in the measured optical fiber 95, and the analyzer 13 measures the temperature distance distribution in the measured optical fiber 95 using the Raman scattering spectrum. ..
　温度及び応力補正手順Ｓ１３２では、分析・表示器１３が、被測定光ファイバ９５の温度及び応力を用いて、線幅算出手順Ｓ１０２で算出した線幅を補正する。 In the temperature and stress correction procedure S132, the analyzer 13 corrects the line width calculated in the line width calculation procedure S102 using the temperature and stress of the optical fiber 95 to be measured.
　ＧＡＷＢＳの線幅と尖度は被覆の音響インピーダンスと線形の関係にあり、音響インピーダンスは温度や応力により線形に変化する。また、ＧＡＷＢＳの強度は、線幅が変化するとそれに合わせて変化する。すなわち、ＧＡＷＢＳは温度及び応力と線形の関係にある。そのため、分析・表示器１３は、測定した温度や応力の距離分布を用いて温度変化及び応力変化を検出し、ＧＡＷＢＳを補正することができる。 The line width and kurtosis of GAWBS have a linear relationship with the acoustic impedance of the coating, and the acoustic impedance changes linearly with temperature and stress. Further, the strength of GAWBS changes as the line width changes. That is, GAWBS has a linear relationship with temperature and stress. Therefore, the analyzer 13 can detect the temperature change and the stress change by using the measured temperature and stress distance distribution, and can correct the GAWBS.
　なお、本実施形態ではスペクトルの線幅を用いる線幅算出手順Ｓ１０２を実行し、線幅を補正する例を示したが、スペクトルを用いた任意の検知方法とその補正に適用することができる。例えば、線幅算出手順Ｓ１０２はピークの周波数の強度を算出する手順であってもよい。この場合ステップＳ１１２、Ｓ１２２、Ｓ１３２においてピークの周波数の強度を補正する。 Although the present embodiment shows an example in which the line width calculation procedure S102 using the line width of the spectrum is executed and the line width is corrected, it can be applied to an arbitrary detection method using the spectrum and its correction. For example, the line width calculation procedure S102 may be a procedure for calculating the intensity of the peak frequency. In this case, the intensity of the peak frequency is corrected in steps S112, S122, and S132.
　本開示は情報通信産業に適用することができる。 This disclosure can be applied to the information and communication industry.
１０：マイクロベンド損失増減傾向検知装置
１１：光源
１２：検出器
１３：分析・表示器
１４：カプラ
１５：サーキュレータ
２１、２２、２３：クロージャ
５１：ＯＴＤＲ
５２：ＢＯＴＤＲ
５３：ＢＯＴＤＡ
９１：基地局
９２、９３、９４：マンホール
９５：被測定光ファイバ 10: Microbend loss increase / decrease tendency detection device 11: Light source 12: Detector 13: Analysis / display 14: Coupler 15: Circulators 21, 22, 23: Closure 51: OTDR
52: BOTDR
53: BOTDA
91: Base stations 92, 93, 94: Manhole 95: Optical fiber to be measured

Claims (5)

  1. 　対象とするマイクロベンドが発生した被測定光ファイバの前方ブリルアン散乱を測定し、
    　前記前方ブリルアン散乱のピーク周辺の特性に基づいて、前記被測定光ファイバのマイクロベンド損失の増減傾向を検知する、
    　装置。     Measure the forward Brillouin scattering of the optical fiber to be measured in which the target microbend is generated,
    Based on the characteristics around the peak of the forward Brillouin scattering, the tendency of increase / decrease in the microbend loss of the optical fiber to be measured is detected.
    Device.
  2. 　前記特性は、前記前方ブリルアン散乱に含まれる少なくとも１つのピークの強度、線幅、尖度、の少なくともいずれかである、
    　請求項１に記載の装置。     The characteristic is at least one of the intensity, line width, and kurtosis of at least one peak contained in the forward Brillouin scattering.
    The device according to claim 1.
  3. 　前記被測定光ファイバの温度及び応力の一方あるいは両方を測定するＯＴＤＲをさらに備え、
    　測定した温度及び応力を用いて前記特性を補正する、
    　請求項１から２のいずれかに記載の装置。     Further equipped with an OTDR that measures one or both of the temperature and stress of the optical fiber to be measured.
    Correcting the above characteristics using the measured temperature and stress,
    The device according to any one of claims 1 and 2.
  4. 　装置が、対象とするマイクロベンドが発生した被測定光ファイバの前方ブリルアン散乱を測定し、
    　前記装置が、前記前方ブリルアン散乱のピーク周辺の特性に基づいて、前記被測定光ファイバのマイクロベンド損失の増減傾向を検知する、
    　方法。     The device measures the forward Brillouin scattering of the optical fiber under test where the microbend of interest occurs.
    The device detects an increase / decrease tendency of the microbend loss of the optical fiber to be measured based on the characteristics around the peak of the forward Brillouin scattering.
    Method.
  5. 　前記装置が、前記被測定光ファイバの温度及び応力の一方あるいは両方をさらに測定し、
    　前記装置が、前記測定の結果を用いて前記特性を補正する、
    　請求項４に記載の方法。     The device further measures one or both of the temperature and stress of the optical fiber to be measured.
    The device corrects the characteristic using the result of the measurement.
    The method according to claim 4.
PCT/JP2020/036026 2020-09-24 2020-09-24 Device and method for detecting trend of increase and decrease of microbending loss in optical fiber WO2022064597A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61104235A (en) * 1984-10-26 1986-05-22 Nippon Telegr & Teleph Corp <Ntt> Method for measuring strain distribution of optical fiber
JP2001033218A (en) * 1999-07-16 2001-02-09 Nippon Telegr & Teleph Corp <Ntt> Optical fiber distortion measuring method and recording medium for realizing the method
JP2008145315A (en) * 2006-12-12 2008-06-26 Nippon Telegr & Teleph Corp <Ntt> Method and device of measuring temperature/distortion of optical fiber
JP2010019605A (en) * 2008-07-08 2010-01-28 Furukawa Electric Co Ltd:The Fiber optic sensor
WO2018193440A1 (en) * 2017-04-20 2018-10-25 Bar-Ilan University Distributed fiber optic sensing using guided acoustic modes

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61104235A (en) * 1984-10-26 1986-05-22 Nippon Telegr & Teleph Corp <Ntt> Method for measuring strain distribution of optical fiber
JP2001033218A (en) * 1999-07-16 2001-02-09 Nippon Telegr & Teleph Corp <Ntt> Optical fiber distortion measuring method and recording medium for realizing the method
JP2008145315A (en) * 2006-12-12 2008-06-26 Nippon Telegr & Teleph Corp <Ntt> Method and device of measuring temperature/distortion of optical fiber
JP2010019605A (en) * 2008-07-08 2010-01-28 Furukawa Electric Co Ltd:The Fiber optic sensor
WO2018193440A1 (en) * 2017-04-20 2018-10-25 Bar-Ilan University Distributed fiber optic sensing using guided acoustic modes

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