公开(公告)号：US20210262892A1

公开(公告)日：2021-08-26

申请号：US17252311

申请日：2019-06-12

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Hiroyuki IIDA ,  Tetsuya MANABE ,  Yusuke KOSHIKIYA ,  Hidenobu HIROTA ,  Takui UEMATSU

IPC: G01M11/00 ,  H04B10/071

Abstract: An object of the present disclosure is to provide a frequency division multiplexing coherent OTDR, a test method, a signal processing apparatus, and a program that can maintain, even in a case where a DFB laser is used, a spatial resolution equivalent to a spatial resolution achieved when a fiber laser or an external resonant laser is used. An OTDR according to the present disclosure includes a light incidence unit configured to change an optical frequency of light from a light source by a predetermined frequency interval at a predetermined time interval to generate test light pulses and cause the test light pulses to sequentially enter a fiber under test, a light reception unit configured to use the light from the light source as local light to coherently detect backscattered light from the fiber under test to acquire a received signal, and a computation unit configured to separate the received signal into signals with frequencies obtained by changing the optical frequency by the predetermined frequency interval, square amplitudes of the signals resulting from frequency separation to generate square values, perform Wiener filter processing on the square values, compensate values resulting from the Wiener filter processing for delay time when the test light pulses are caused to enter the fiber under test, and calculate an arithmetic mean of the compensated values.

公开(公告)号：US20220113220A1

公开(公告)日：2022-04-14

申请号：US17268113

申请日：2019-08-16

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Atsushi NAKAMURA ,  Keiji OKAMOTO ,  Tetsuya MANABE

IPC: G01M11/00

Abstract: An object of the present invention is to provide a Raman gain efficiency distribution testing method and a Raman gain efficiency distribution testing apparatus for measuring a Raman gain efficiency distribution of a fundamental mode and a first high-order mode in a few-mode fiber. The Raman gain efficiency distribution testing method and the Raman gain efficiency distribution testing apparatus according to the present invention compute a Raman gain coefficient of a tested optical fiber from a Raman gain coefficient of a pure quartz core optical fiber at an excitation wavelength of 1 μm, a wavelength of excitation light, and a relative refractive index difference between a core and a clad at an arbitrary position z, compute electric field distribution overlap integrals at an arbitrary position z, between modes, of a mode field diameter of each mode at a wavelength of signal light, and a mode field diameter of each mode at a wavelength of excitation light; and compute the product of the Raman gain coefficient and the electric field distribution overlap integrals, and acquire Raman gain efficiencies, between modes, of the signal light and the excitation light at the arbitrary position z.

公开(公告)号：US20210223095A1

公开(公告)日：2021-07-22

申请号：US15734211

申请日：2019-05-29

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Yoshifumi WAKISAKA ,  Daisuke IIDA ,  Kunihiro TOGE ,  Tetsuya MANABE

IPC: G01H9/00 ,  G01B17/04 ,  G01D5/353

Abstract: An object is to provide an optical fiber path search method, an optical fiber path search system, a signal processor, and a program that can be operated free of the effects of walls, supporting members, and the like so that only a signal generated by an acoustic wave propagating through the air can be extracted. An optical fiber path search system according to the present invention utilizes DAS and includes: a vibration source 304 configured to provide an acoustic wave to a predetermined region; a light reflection measurement device 305 configured to be connected to one end of an optical fiber 302 and configured to measure vibration of a change in an optical path length from the other end of the optical fiber 302 to a point in the optical fiber 302 due to the acoustic wave provided by the vibration source 304; and a signal processor 313 configured to extract a signal component in a high frequency region higher than a preset cutoff frequency from a signal of the vibration of the change in the optical path length measured by the light reflection measurement device 305 and calculate a distance between the vibration source 304 and the point in the optical fiber 302 using the signal component.

公开(公告)号：US20230280536A1

公开(公告)日：2023-09-07

申请号：US18016438

申请日：2020-07-21

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Tatsuya FUJIMOTO ,  Hidenobu HIROTA ,  Takui UEMATSU ,  Tomohiro KAWANO ,  Hiroyuki IIDA ,  Ryo KOYAMA ,  Tetsuya MANABE ,  Kazunori KATAYAMA

IPC: G02B6/28

CPC classification number: G02B6/2821

Abstract: An object of the present disclosure is to provide an optical coupling device capable of controlling a coupling index of optical coupling between two optical fibers for coupling. An optical coupling device of the present disclosure includes two optical fibers for coupling having a core and a clad, and a refractive index variable member to change the refractive index by irradiation with light between the two optical fibers for coupling.

公开(公告)号：US20210239567A1

公开(公告)日：2021-08-05

申请号：US16973396

申请日：2019-06-04

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Hiroyuki IIDA ,  Tetsuya MANABE ,  Yusuke KOSHIKIYA ,  Hidenobu HIROTA ,  Takui UEMATSU

IPC: G01M11/00 ,  G01M11/02 ,  A61B5/024 ,  H04B10/071

Abstract: An object of the present invention is to provide an optical pulse test apparatus that can test an optical fiber cable at once in a short period of time. The optical pulse test apparatus according to the present invention includes: an optical pulse signal generation unit 11 that emits an optical pulse with a width that is n times as large as a pulse width T corresponding to desired spatial resolution; a light reception unit 12 that receives reflected light and back-scattered light from n FUTs; an optical path control unit 13 that switches paths connected to the n FUTs are connected at an interval T, inject the optical pulse, as a test optical pulse having the pulse width T, sequentially into the paths, then switches the paths at an interval ts that is shorter than the time period T, and emit the reflected light and the back-scattered light from the n FUTs sequentially onto the light reception unit 12 at an interval n×ts; and an arithmetic processing unit 14 that divides the electrical signal output from the light reception unit 12, with an interval equal to the interval ts at which switching the paths is performed, into discrete signals respectively corresponding to the FUTs, and calculates the reflectance distributions of the reflected light and the back-scattered light of the respective FUTs.

公开(公告)号：US20230314715A1

公开(公告)日：2023-10-05

申请号：US18019113

申请日：2020-08-07

Applicant: Nippon Telegraph and Telephone Corporation

Inventor： Tatsuya Fujimoto ,  Hidenobu HIROTA ,  Takui UEMATSU ,  Tomohiro Kawano ,  Hiroyuki IIDA ,  Ryo Koyama ,  Tetsuya MANABE ,  Kazunori Katayama

IPC: G02B6/28

CPC classification number: G02B6/2821

Abstract: An object of the present disclosure is to provide an optical coupling device capable of controlling a coupling rate of optical coupling between two coupling optical fibers.
An optical coupling device of the present disclosure includes two coupling optical fibers each including a core and a clad and, between the two coupling optical fibers, a thickness variable member having a thickness between the two coupling optical fibers that varies by irradiation with light.

公开(公告)号：US20210231892A1

公开(公告)日：2021-07-29

申请号：US17266071

申请日：2019-08-09

Applicant: Nippon Telegraph and Telephone Corporation

Inventor： Takui UEMATSU ,  Hidenobu HIROTA ,  Hiroyuki IIDA ,  Tetsuya MANABE

IPC: G02B6/42

Abstract: An object is to provide an optical fiber side input and output device in which light can be input and output from the side of the tube core cable without adjusting a spacing S even in a case where the thickness of the protective tube differs, and a method of designing the optical fiber side input and output device. An optical fiber side input and output device according to the present invention has a structure in which an angle of a central angle of an apex portion of a first jig having a convex portion is appropriately set, and a loss insertion is kept equal to or less than a prescribed value by using a relationship between a spacing S at the angle and an insertion loss when light is input and output from the side of the tube core cable, even in a case which a thickness of a protective tube changes, and this eliminates the need of adjusting the spacing S.

公开(公告)号：US20210003474A1

公开(公告)日：2021-01-07

申请号：US16977882

申请日：2019-03-05

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Yusuke KOSHIKIYA ,  Atsushi NAKAMURA ,  Kazutaka NOTO ,  Tetsuya MANABE

IPC: G01M11/00

Abstract: An object of the present disclosure is to provide an optical fiber cable monitoring method and an optical fiber cable monitoring system capable of linking information obtained from a measurement result with information stored in a DB and accurately specifying a loss occurrence location on an optical fiber cable. The optical fiber cable monitoring method according to the present disclosure uses two types of optical fiber measurement techniques having different sensitivities. Each of closure locations on the optical fiber cable is acquired with a high-sensitivity measurement technique, and geographical location information and the closure locations on the optical fiber are linked in an arrangement order of the closures. Thus, an operator can recognize an actual location (geographical location information) of a closure that is linked to a location of a point of abnormality on the optical fiber cable when an abnormality in the closure is detected with a low-sensitivity measurement technique.

公开(公告)号：US20210195303A1

公开(公告)日：2021-06-24

申请号：US17271390

申请日：2019-08-23

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Takui UEMATSU ,  Tetsuya MANABE ,  Hidenobu HIROTA ,  Hiroyuki IIDA

IPC: H04Q11/00 ,  H04L12/46 ,  H04B10/079

Abstract: The present disclosure intends to provide an optical signal from an ONU according to a desired service usage state without using the ONU and an OLT. A simulated signal light generation apparatus 10 according to the present disclosure is a simulated signal light generation apparatus 10 for simulating an uplink signal light generated in an optical network unit (ONU) in a passive optical network (PON), and the apparatus includes a usage state control unit 11 that sets a service usage state of the ONU, a signal generation unit 12 that generates an uplink signal frame according to the usage state set by the usage state control unit 11, and an electrical/optical conversion unit 13 that converts an electrical signal from the signal generation unit 12 into an optical signal, and the optical signal from the electrical/optical conversion unit 13 is repeatedly transmitted to an optical fiber core 22.

公开(公告)号：US20210191043A1

公开(公告)日：2021-06-24

申请号：US17053048

申请日：2019-04-26

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Takui UEMATSU ,  Hidenobu HIROTA ,  Hiroyuki IIDA ,  Tetsuya MANABE

IPC: G02B6/28

Abstract: An object of the present invention is to provide a probe optical fiber and a local-light coupling apparatus for an optical fiber that can input light with high efficiency without performing input efficiency measurement or probe alignment. The present invention is a probe optical fiber of which a tip is close to a bent part of a coated optical fiber disposed in a local-light coupling apparatus for an optical fiber, and which inputs and outputs light to and from the bent part of the coated optical fiber, wherein light emitted from the tip has a light intensity profile in which in the bent part of the coated optical fiber, relative to a light intensity in a center of an optical axis, a decrease in light intensity at a position separated by 20 μm from the optical axis is less than 17.6 dB.