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WO2025062512A1 - Procédé de mesure de torsion dans des fibres multicœurs couplées - Google Patents

Procédé de mesure de torsion dans des fibres multicœurs couplées Download PDF

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Publication number
WO2025062512A1
WO2025062512A1 PCT/JP2023/034016 JP2023034016W WO2025062512A1 WO 2025062512 A1 WO2025062512 A1 WO 2025062512A1 JP 2023034016 W JP2023034016 W JP 2023034016W WO 2025062512 A1 WO2025062512 A1 WO 2025062512A1
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WO
WIPO (PCT)
Prior art keywords
core
coupled
twist
points
mcf
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Pending
Application number
PCT/JP2023/034016
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English (en)
Japanese (ja)
Inventor
真輝 中森
篤志 中村
佳史 脇坂
優介 古敷谷
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NTT Inc
Original Assignee
Nippon Telegraph and Telephone Corp
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Filing date
Publication date
Application filed by Nippon Telegraph and Telephone Corp filed Critical Nippon Telegraph and Telephone Corp
Priority to PCT/JP2023/034016 priority Critical patent/WO2025062512A1/fr
Publication of WO2025062512A1 publication Critical patent/WO2025062512A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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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
    • 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
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating

Definitions

  • This disclosure relates to a method for measuring the twist of a coupled multicore fiber.
  • SDM space division multiplexing
  • MCF coupled multicore fiber
  • Non-Patent Document 1 A method for measuring the twist of uncoupled MCF has been proposed (Non-Patent Document 1).
  • the twist is measured from the change in the backscattering pattern when there is no twist and when there is a twist. Since this change in pattern corresponds to the distortion caused by the twist, the amount of distortion applied to the fiber can be measured from the change in the pattern.
  • the twist in the entire fiber is measured by measuring the distortion for each core.
  • Non-Patent Document 1 measures the distortion caused by twisting, but it is not possible to measure the twist of the entire fiber.
  • the purpose of this disclosure is to make it possible to measure the twist of bonded MCF.
  • the measurement device and method disclosed herein measure the twist in a coupled MCF based on the distance between the points where the intensity of light coupled from a first core to a second core in the coupled MCF is greatest.
  • the measuring device of the present disclosure may include a backscattered light waveform measuring device that irradiates test light onto a first end face of the first core of the coupled MCF and measures the intensity of the backscattered light emitted from the first end face of the second core.
  • the measuring device may measure the twist in the coupled MCF based on the distance between points where the intensity of the backscattered light is greatest.
  • the present disclosure utilizes the fact that the distance between two points where the backscattered light intensity changes sharply coincides with the distance between two points where the propagation constant between cores coincides due to twisting.
  • the measurement device disclosed herein may measure the twist based on the fact that the twist per distance between the points corresponds to a rotation angle according to the number of cores in the coupled multicore fiber.
  • the present disclosure makes it possible to measure the twist of a bonded MCF.
  • FIG. 1 is a diagram illustrating a twisted state of a coupled MCF.
  • FIG. 11 is an explanatory diagram showing an example of a change in the difference in propagation constant between cores when a coupled MCF is twisted.
  • FIG. 2 is an explanatory diagram of the measurement principle of the present disclosure.
  • FIG. 2 is an illustration of a backscatter waveform measured in the present disclosure. 2 illustrates an example of the configuration of a measurement device according to the present disclosure.
  • 1 is a flowchart illustrating an example of a measurement method according to the present disclosure. 1 is an example of a measurement result obtained using the measurement method of the present disclosure.
  • FIG. 11 is an explanatory diagram of the measurement principle of the present disclosure when the number of cores is three.
  • the laid optical fiber is twisted at a certain rate. Therefore, when a coupled MCF 91 having two cores in the cladding is bent or twisted at a radius R, the positions of the cores C1 and C2 in the cross section of the optical fiber change, as shown in Figure 1.
  • the change in the positions of the cores C1 and C2 in the cross section of the coupled MCF 91 can be considered as rotation. Therefore, the twist rate of the coupled MCF 91 corresponds to the amount of rotation of the cores C1 and C2. Therefore, in this disclosure, the amount of rotation per unit length [rad/m] is measured as the twist rate.
  • Figure 2 shows the change in the propagation constant difference between cores in the longitudinal direction when a two-core coupled MCF 91 is bent, and the appearance (rotation) of the cross section of the fiber at that time.
  • the refractive index of the outer core and the inner core changes relatively in the longitudinal direction with respect to the bending radius, and the propagation constant also changes accordingly. Therefore, as shown in Figure 2, the propagation constant difference between the cores changes periodically.
  • the distance between the points where light between the cores couples that is, the coupling section Dh
  • the twist is measured based on the fact that the twist per coupling section Dh corresponds to the rotation angle according to the number of cores in the coupled MCF 91.
  • Figure 3 shows the concept of a method for measuring twist.
  • the radius R and twist are omitted from the drawing.
  • at least one of bending and twisting is applied.
  • the coupled MCF 91 shows an example of a coupled optical fiber including two cores.
  • Test light is incident on core C1 from the left side of Figure 3.
  • the test light propagates through core C1 from left to right.
  • the first point where the difference in propagation constant is 0 is called D1.
  • part of the test light propagating through core C1 transfers to core C2 and travels through core C2 to the right.
  • the next point where the propagation constant difference is 0 is D2.
  • the same phenomenon occurs, and the test light moves from core C1 to core C2 and travels to the right in Figure 3.
  • the test light propagates through cores C1 and C2 to the right in Figure 3.
  • the method shown in FIG. 3 is used to input test light to one core C1 of a coupled MCF 91, and measure the backscattered light from the core C2 adjacent to the core C1 to which the test light is input (adjacent core).
  • FIG 4 shows an overview of the measured backscattered light intensity.
  • the measured backscattered light intensity waveform has the optical fiber distance on the horizontal axis and the backscattered light intensity on the vertical axis.
  • the distance between points D1 and D2 corresponds to half a turn of the twist of the coupled MCF 91.
  • the twist per unit length is measured using the coupling section Dh defined by points D1 and D2.
  • the measurement device 90 of this embodiment includes a frequency domain reflectometer 92, a circulator 93, a fan-in/fan-out device 94, and an arithmetic processing unit 95.
  • the frequency domain reflectometer 92 is connected to a first end face 91A of a coupled MCF 91.
  • the frequency domain reflectometer 92 can be any backscattered light waveform measuring device with high distance resolution.
  • FIG. 6 is a flowchart showing an example of a torsion measuring method according to the present disclosure.
  • the frequency domain reflectometer 92 measures the intensity of backscattered light from the adjacent core C2 of the coupled MCF 91 (S11).
  • the frequency domain reflectometer 92 inputs test light to a first end face of the first core C1 of the coupled MCF 91, and measures the intensity of the backscattered light that is scattered by the coupled MCF 91 and emitted from the first end face of the second core C2 of the coupled MCF 91.
  • the frequency domain reflectometer 92 inputs test light to a first end face 91A of a core C1 in the coupled MCF 91.
  • the core C1 to which the test light is input may be referred to as an input core or a first core.
  • the test light output from the frequency domain reflectometer 92 passes through a circulator 93 and a fan-in/fan-out device 94, and is input to the core C1.
  • the frequency domain reflectometer 92 measures the intensity of the backscattered light emitted from the first end face 91A of the core C2 adjacent to the core C1.
  • the core C2 adjacent to the core C1 may be referred to as the adjacent core or the second core.
  • the core C2 may be any core to which the propagating light of the core C1 couples.
  • the backscattered light intensity from core C2 passes through a fan-in/fan-out device 94 and a circulator 93, and is measured by a frequency domain reflectometer 92.
  • a frequency domain reflectometer 92 By using the circulator 93, it is possible to measure the backscattered light intensity from the adjacent core C2 using a compact configuration.
  • Figure 7 shows an example of the backscattered light intensity obtained by step S11.
  • Figure 7 shows the actual backscattered light intensity measured for a coupled MCF 91 using the measurement system of Figure 5.
  • the calculation processing unit 95 detects two points D1 and D2 where the backscattered light intensity changes sharply from the distance distribution of the backscattered light intensity. As shown in Figure 7, two points D1 and D2 where the backscattered light intensity changes sharply were confirmed in the actual measurement.
  • the arithmetic processing unit 95 calculates the twist in the coupled MCF based on the distance between the points where the intensity of the backscattered light is high (S12, S13). For example, the arithmetic processing unit 95 detects two points where the intensity of the backscattered light changes sharply (S12), and calculates the twist rate from the distance between the two detected points (S13).
  • step S13 the calculation processing unit 95 calculates the twist rate using the coupling section Dh.
  • the distance between points D1 and D2 is 2.86 m.
  • FIG. 8 shows an example of application to a coupled MCF with three cores.
  • Test light is incident on core C1 of coupled MCF 91, and the test light transitions to each core at points where the propagation constant difference between core C2 and core C3 is zero.
  • the test light couples to core C2 at points D1 and D2 where the propagation constant difference between core C2 is zero, and the test light couples to core C3 at points D3 and D4 where the propagation constant difference between core C3 is zero.
  • the frequency domain reflectometer 92 measures the backscattered light of cores C2 and C3.
  • the processor 95 then executes step S12 shown in FIG. 6 for each of cores C2 and C3. This detects points D1 and D2 in core C2 and points D1 and D2 in core C3.
  • step S13 the calculation processing unit 95 calculates the bonded section Dh1 in core C2 from points D1 and D2 in core C2, and calculates the bonded section Dh2 in core C3 from points D1 and D2 in core C3.
  • the calculation processing unit 95 then calculates the first torsion rate using the bonded section Dh1, and calculates the second torsion rate using the bonded section Dh2.
  • the calculation processing unit 95 then uses the first and second torsion rates to determine the torsion rate of the bonded MCF 91. At this time, the calculation processing unit 95 may calculate the average of the first and second torsion rates, or may select one of them.
  • the torsion of the bonded MCF 91 can be measured.
  • examples with two and three cores are shown, but the torsion rate of the bonded MCF 91 can be obtained by performing a similar measurement even if the number of cores is four or more.
  • a backscattered light waveform measuring device is connected to the first end face 91A of the coupled MCF 91.
  • the backscattered light waveform measuring device can determine the longitudinal distance of the coupled MCF 91 at which the twist rate is measured. Therefore, it is possible to determine at which point the coupled MCF 91 is laid and at what twist rate it is laid. Note that this disclosure is not limited to the twist rate of the coupled MCF 91, and any method that can be quantified to evaluate the twist of the coupled MCF 91 can be adopted.
  • the designed optical characteristics cannot be obtained.
  • unexpected twists can cause a decrease in communication quality.
  • the present disclosure makes it possible to accurately grasp the twists in the coupled MCF 91, thereby obtaining the designed characteristics and improving communication services using the coupled MCF.

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

Abstract

La présente divulgation concerne un procédé de mesure de torsion dans des fibres multicœurs couplées, le procédé consistant en : le fait d'amener une lumière de test à être incidente sur une première surface d'extrémité d'un premier cœur disposé dans une fibre multicœur couplée ; la mesure de l'intensité de la lumière rétrodiffusée résultant de la diffusion de la lumière de test par la fibre multicœur couplée et émise à partir de la première surface d'extrémité d'un second cœur disposé dans la fibre multicœur couplée ; et la mesure de la torsion dans la fibre multicœur couplée sur la base de la distance entre des points auxquels l'intensité de la lumière rétrodiffusée augmente.
PCT/JP2023/034016 2023-09-20 2023-09-20 Procédé de mesure de torsion dans des fibres multicœurs couplées Pending WO2025062512A1 (fr)

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PCT/JP2023/034016 WO2025062512A1 (fr) 2023-09-20 2023-09-20 Procédé de mesure de torsion dans des fibres multicœurs couplées

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120069347A1 (en) * 2010-09-17 2012-03-22 Luna Innovations Incorporated Compensating for non-ideal multi-core optical fiber structure
JP2013505441A (ja) * 2009-09-18 2013-02-14 ルナ イノベーションズ インコーポレイテッド 光学的位置および／または形状センシング
JP2019511706A (ja) * 2016-02-24 2019-04-25 コーニンクレッカ フィリップス エヌ ヴェＫｏｎｉｎｋｌｉｊｋｅ Ｐｈｉｌｉｐｓ Ｎ．Ｖ． 縒られたマルチコアファイバを用いる光学形状感知における非線形ねじれ応答を補正する方法及びシステム
US20190234726A1 (en) * 2016-06-09 2019-08-01 Intuitive Surgical Operations, Inc. Methods and apparatus for calibration for a fiber optic shape sensor
CN111555803A (zh) * 2020-05-22 2020-08-18 中天宽带技术有限公司 双向多芯光纤串扰计算方法、装置及计算机可读存储介质

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013505441A (ja) * 2009-09-18 2013-02-14 ルナ イノベーションズ インコーポレイテッド 光学的位置および／または形状センシング
US20120069347A1 (en) * 2010-09-17 2012-03-22 Luna Innovations Incorporated Compensating for non-ideal multi-core optical fiber structure
JP2019511706A (ja) * 2016-02-24 2019-04-25 コーニンクレッカ フィリップス エヌ ヴェＫｏｎｉｎｋｌｉｊｋｅ Ｐｈｉｌｉｐｓ Ｎ．Ｖ． 縒られたマルチコアファイバを用いる光学形状感知における非線形ねじれ応答を補正する方法及びシステム
US20190234726A1 (en) * 2016-06-09 2019-08-01 Intuitive Surgical Operations, Inc. Methods and apparatus for calibration for a fiber optic shape sensor
CN111555803A (zh) * 2020-05-22 2020-08-18 中天宽带技术有限公司 双向多芯光纤串扰计算方法、装置及计算机可读存储介质

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