WO2024252658A1 - Procédé et dispositif de mesure du coefficient de couplage de puissance d'une fibre optique multicœur - Google Patents

Procédé et dispositif de mesure du coefficient de couplage de puissance d'une fibre optique multicœur Download PDF

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Publication number
WO2024252658A1
WO2024252658A1 PCT/JP2023/021500 JP2023021500W WO2024252658A1 WO 2024252658 A1 WO2024252658 A1 WO 2024252658A1 JP 2023021500 W JP2023021500 W JP 2023021500W WO 2024252658 A1 WO2024252658 A1 WO 2024252658A1
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Prior art keywords
core
power coupling
coupling coefficient
light intensity
backscattered light
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PCT/JP2023/021500
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English (en)
Japanese (ja)
Inventor
真輝 中森
篤志 中村
優介 古敷谷
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NTT Inc
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Nippon Telegraph and Telephone Corp
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Priority to JP2025525903A priority Critical patent/JPWO2024252658A1/ja
Priority to PCT/JP2023/021500 priority patent/WO2024252658A1/fr
Publication of WO2024252658A1 publication Critical patent/WO2024252658A1/fr
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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
    • G01M11/02—Testing optical properties

Definitions

  • This disclosure relates to a method and apparatus for measuring the power coupling coefficient of a multi-core optical fiber.
  • Non-Patent Document 1 discloses a method for measuring the power coupling coefficient of homogeneous core MCFs with uniform core characteristics.
  • an object of the present invention is to provide a power combining coefficient measurement method and device that take into account the asymmetry between cores.
  • the power coupling coefficient measurement method of the present invention uses the intensity ratio at a distance where the backscattered light intensity ratio becomes constant to approximately determine the power coupling coefficient.
  • a power coupling coefficient measurement method is a method for measuring a power coupling coefficient of a multi-core optical fiber in which the power coupling coefficient between cores is asymmetric, the method comprising the steps of: Injecting test light into an input core, which is one of the cores, at one end of the multi-core optical fiber; measuring, at one end of the multi-core optical fiber, a backscattered light intensity of backscattered light output from the input core and an adjacent core adjacent to the input core; calculating a ratio between the backscattered light intensity of the incident core and the backscattered light intensity of the adjacent core from a distance where a backscattered light intensity ratio becomes steady in a longitudinal direction from one end of the multi-core optical fiber; and substituting the backscattered light intensity of the incident core and the adjacent core at an arbitrary point in a longitudinal direction from one end of the multi-core optical fiber and the ratio into a calculation formula to calculate the power coupling coefficient between the cores.
  • a power coupling coefficient measurement device is a device for measuring a power coupling coefficient of a multi-core optical fiber in which the power coupling coefficient between cores is asymmetric, the device comprising: Injecting test light into an input core, which is one of the cores, at one end of the multi-core optical fiber; and measuring backscattered light intensity of backscattered light output from the input core and an adjacent core adjacent to the input core, at one end of the multi-core optical fiber.
  • a measuring instrument for performing the above-mentioned a calculator for calculating a ratio between the backscattered light intensity of the incident core and the backscattered light intensity of the adjacent core from a distant point where a backscattered light intensity ratio becomes steady in a longitudinal direction from one end of the multi-core optical fiber, and for calculating the power coupling coefficient between the cores by substituting the backscattered light intensity of the incident core and the adjacent core at an arbitrary point in a longitudinal direction from one end of the multi-core optical fiber and the ratio into a calculation formula; Equipped with.
  • the power coupling coefficient measurement method of the present invention approximately obtains the power coupling coefficient by utilizing the fact that, in a distant location, the ratio of the backscattered light intensity P bs2 of the adjacent core to the backscattered light intensity P bs1 of the incident core is equal to the ratio of the power coupling coefficient h 21 from the adjacent core to the incident core to the power coupling coefficient h 12 from the incident core to the adjacent core (the following formula).
  • the present invention can provide a method and device for measuring the power coupling coefficient that takes into account the asymmetry between cores.
  • h21 is the power coupling coefficient from the adjacent core to the incident core
  • h12 is the power coupling coefficient from the incident core to the adjacent core
  • r is the ratio
  • z is the distance (m) from the one end to the arbitrary point
  • P bs1 (z) is the backscattered light intensity (dB) from the arbitrary point measured at the input core
  • P bs2 (z) is the backscattered light intensity (dB) from the arbitrary point measured at the adjacent core. It is.
  • the computing unit can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network.
  • the present invention can provide a method and device for measuring the power coupling coefficient that takes into account the asymmetry between cores.
  • FIG. 2 is a diagram illustrating a power coupling coefficient.
  • 1 is a diagram illustrating a power coupling coefficient measuring method according to the present invention
  • 1 is a diagram illustrating a power coupling coefficient measurement device according to the present invention
  • 1 is a diagram for explaining the intensity of backscattered light from each core of a measured optical fiber 50 acquired by a measuring instrument 11 of the power coupling coefficient measurement device according to the present invention
  • 1 is a diagram illustrating a power coupling coefficient of a heterogeneous-core MCF (two cores) measured by a power coupling coefficient measurement device according to the present invention.
  • FIG. 13 is a diagram for explaining points to note regarding backscattered light intensity.
  • 1 is a diagram for explaining a power coupling coefficient measured by a power coupling coefficient measurement device according to the present invention
  • Comparative Example A method for measuring the power coupling coefficient in an MCF with homogeneous cores will be described as a comparative example.
  • the MCF will be explained using a two-core fiber.
  • test light with optical intensity P0 is incident on the incident core (core1)
  • the relationship between the optical intensities of each core at position z in the longitudinal direction from the incident end is described by the power coupling equation in formula (1). Since the cores are of the same type, the power coupling coefficients of each core can be set to the same value h.
  • P 1 (z) is the light intensity at position z of the input core (core1)
  • P 2 (z) is the optical intensity at position z of the adjacent core (core 2)
  • ⁇ 1 is the loss per unit length of the input core (core1)
  • ⁇ 2 is the loss per unit length of the adjacent core (core2)
  • the backscattered light intensity (P bs1 (z), P bs2 (z)) of each core at position z can be expressed as follows: where ⁇ s (z) is the scattering coefficient at position z, and B(z) is the capture rate at position z. Therefore, the power coupling coefficient h can be obtained from the ratio of the backscattered light intensities.
  • the backscattered light intensity (P bs1 (z), P bs2 (z)) of each core at position z can be expressed as follows: where ⁇ s (z) is the scattering coefficient at position z, and B(z) is the capture rate at position z.
  • equation (8) the power coupling coefficient of each core of the heterogeneous core coupled MCF can be calculated as follows.
  • Example 2 3 is a diagram illustrating an apparatus 301 for measuring the power coupling coefficient of an MCF, which is an optical fiber 50 to be measured.
  • the apparatus 301 includes a measuring device 11, a computing device 12, and an optical branching component 13.
  • the optical branching component 13 can input light from the measuring device 11 to any core of the MCF and input light from any core of the MCF to the measuring device 11.
  • the optical branching component 13 is, for example, a fan-in/fan-out component.
  • the MCF of the test optical fiber 50 has an asymmetric power coupling coefficient between the cores.
  • the measuring instrument 11 is Injecting test light into an input core, which is one of the cores, at one end of the multi-core optical fiber; and measuring backscattered light intensities (P bs1 (z), P bs2 (z)) of backscattered light output from the input core and an adjacent core adjacent to the input core, at one end of the multi-core optical fiber.
  • the measuring instrument 11 is, for example, an OFDR (OFDR).
  • the calculator 12 is Calculating a ratio r between the backscattered light intensity of the incident core and the backscattered light intensity of the adjacent core from a distance where the backscattered light intensity ratio becomes steady in the longitudinal direction from one end of the multi-core optical fiber; and Substituting the backscattered light intensity of the incident core and the adjacent core at an arbitrary point z in the longitudinal direction from one end of the multi-core optical fiber and the ratio into calculation formula (11) to calculate the power coupling coefficients ( h21 , h12 ) between the cores.
  • "far” means a region where the backscattered light intensity ratio is constant. For example, in the case of the optical fiber in FIG. 4, it is a region where z ⁇ 50 m. Note that the "far” region differs depending on the optical fiber, so it does not always mean that 50 m or more is far.
  • the device 301 measures the backscattered light intensity P bs1 (z) from the incident core using a circuit as shown in Fig. 3(a). Next, the device 301 measures the backscattered light intensity P bs2 (z) from the adjacent core using a circuit as shown in Fig. 3(b). Note that reference numeral 14 denotes an optical circulator.
  • FIG. 4 is a diagram for explaining the backscattered light intensity from each core of the measured optical fiber 50 acquired by the measuring instrument 11.
  • the horizontal axis is the position z (m), and the vertical axis is the backscattered light intensity (dB).
  • P bs1 (z 0 ) -109.062 dB
  • P bs2 (z 0 ) -110.609 dB.
  • the ratio r in equation (9) can be calculated as follows:
  • Fig. 5 is a diagram for explaining the power coupling coefficients of a heterogeneous-core MCF (2 cores) calculated by equation (11) to which the ratio r in equation (12) is applied.
  • the horizontal axis is the position z, and the vertical axis is the power coupling coefficient at each position.
  • the white line is h12
  • the black line is h21 .
  • the device 301 measures the backscattered light intensity from each of the first core and the second core when test light is incident on the first core of the MCF, and calculates the power coupling coefficients h12 and h21 by utilizing the fact that the ratio of the backscattered light intensity Pbs2 of the second core to the backscattered light intensity Pbs1 of the first core is equal to the ratio of the power coupling coefficient h21 from the second core to the first core to the power coupling coefficient h12 from the first core to the second core at a long distance.
  • the apparatus 301 can measure the power coupling coefficient between the cores of an MCF in which the characteristics of each core are different, which was previously impossible to measure.
  • Equation (5) can be rearranged to obtain equation (A1).
  • equation (A1) becomes as follows.
  • equation (A2) is:
  • equation (A4) can be written as follows:
  • Measuring instrument 12 Calculating unit 13: Optical branching component 14: Optical circulator 15: Test optical fiber (MCF) 301: Equipment

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Testing Of Optical Devices Or Fibers (AREA)

Abstract

Le but de la présente invention est de fournir : un procédé de mesure d'un coefficient de couplage de puissance en tenant compte de l'asymétrie entre des cœurs ; et un dispositif associé.　Le dispositif selon la présente invention comprend : un appareil de mesure 11 qui amène, à une extrémité d'une fibre optique multicœur, une lumière de test à être incidente sur un cœur incident qui est l'un des cœurs, et mesure, au niveau de la première extrémité de la fibre optique multicœur, l'intensité de lumière rétrodiffusée de la lumière rétrodiffusée émise par le cœur incident et un cœur adjacent adjacent à celui-ci ; et une unité de calcul (12) qui calcule un rapport entre l'intensité de lumière rétrodiffusée du cœur incident et l'intensité de lumière rétrodiffusée du cœur adjacent à partir d'une position distante à laquelle le rapport d'intensité de lumière rétrodiffusée devient stationnaire dans la direction longitudinale à partir de ladite extrémité de la fibre optique multicœur, et calcule un coefficient de couplage de puissance entre les cœurs par substitution, à une formule de calcul, du rapport et des intensités de lumière rétrodiffusée du cœur incident et du cœur adjacent à un point arbitraire dans la direction longitudinale à partir de ladite extrémité de la fibre optique multicœur.
PCT/JP2023/021500 2023-06-09 2023-06-09 Procédé et dispositif de mesure du coefficient de couplage de puissance d'une fibre optique multicœur Ceased WO2024252658A1 (fr)

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PCT/JP2023/021500 WO2024252658A1 (fr) 2023-06-09 2023-06-09 Procédé et dispositif de mesure du coefficient de couplage de puissance d'une fibre optique multicœur

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US12540878B2 (en) * 2021-09-16 2026-02-03 Ntt, Inc. Connection loss difference measurement method, equipment and program

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012202827A (ja) * 2011-03-25 2012-10-22 Tohoku Univ マルチコア光ファイバ用モード結合測定方法および測定装置
WO2013027776A1 (fr) * 2011-08-25 2013-02-28 国立大学法人横浜国立大学 Fibre multicœur et procédé de positionnement d'un cœur de fibre multicœur
JP2021012226A (ja) * 2019-07-03 2021-02-04 住友電気工業株式会社 マルチコア光ファイバ
JP2022111486A (ja) * 2021-01-20 2022-08-01 日本電信電話株式会社 光学特性測定装置及び方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012202827A (ja) * 2011-03-25 2012-10-22 Tohoku Univ マルチコア光ファイバ用モード結合測定方法および測定装置
WO2013027776A1 (fr) * 2011-08-25 2013-02-28 国立大学法人横浜国立大学 Fibre multicœur et procédé de positionnement d'un cœur de fibre multicœur
JP2021012226A (ja) * 2019-07-03 2021-02-04 住友電気工業株式会社 マルチコア光ファイバ
JP2022111486A (ja) * 2021-01-20 2022-08-01 日本電信電話株式会社 光学特性測定装置及び方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
NAKAZAWA M. ET AL.: "Nondestructive measurement of mode couplings along a multi-core fiber using a synchronous multi-channel OTDR", OPTICS EXPRESS, vol. 20, no. 11, 18 May 2012 (2012-05-18), pages 12530 - 12540, XP055909442 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US12540878B2 (en) * 2021-09-16 2026-02-03 Ntt, Inc. Connection loss difference measurement method, equipment and program

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