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21.发明授权公开(公告)号：US11815421B2
公开(公告)日：2023-11-14
申请号：US17434949
申请日：2020-02-19
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Yuto Sagae , Takashi Matsui , Kyozo Tsujikawa , Kazuhide Nakajima
IPC: G01M11/00
CPC classification number: G01M11/319
Abstract: An objective is to provide an acoustic mode propagation speed measurement method and an acoustic mode propagation speed measurement device capable of measuring a propagation speed of an acoustic mode without cutting or processing an optical fiber wire.
According to the present invention, an acoustic mode propagation speed measurement method includes: acquiring a frequency shift spectrum of Brillouin scattered light generated in an optical fiber; fitting the frequency shift spectrum using a Gauss function; acquiring a spectral full-width at half maximum w from a fitted curve using the Gauss function; and calculating a propagation speed VA of an acoustic mode of the optical fiber by substituting the acquired spectral full-width at half maximum w into a linear function of the spectral full-width at half maximum w and the propagation speed VA of the acoustic mode.-
公开(公告)号：US11762144B2
公开(公告)日：2023-09-19
申请号：US17422791
申请日：2020-01-06
Applicant: Nippon Telegraph and Telephone Corporation
Inventor： Takashi Matsui , Kazuhide Nakajima
CPC classification number: G02B6/02042 , G02B6/02004 , G02B27/0012
Abstract: A multi-core optical fiber includes: four cores arranged in a lattice shape along a longitudinal direction, each of the four cores having a step-index type refractive index distribution with a radius a; and a cladding region having a lower refractive index than that of each core and a diameter of 125±1 μm and provided on an outer peripheral portion of each core, where an absolute value of a relative refractive index difference between each core and the cladding region is Δ. The four cores are arranged so that a relationship between a minimum distance from the center of each core to an outer periphery of the cladding region, a minimum value Λ of spacing between the cores, and the MFD satisfies a formula, and the radius a of each core and the relative refractive index difference Δ between the core and the cladding region are set.
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公开(公告)号：US11722223B2
公开(公告)日：2023-08-08
申请号：US17634193
申请日：2019-08-19
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Yuto Sagae , Takashi Matsui , Taiji Sakamoto , Kazuhide Nakajima
CPC classification number: H04B10/613 , H04B1/0483 , H04B10/61
Abstract: An objective of the present invention is to provide an optical communication system and an optical communication method that can reduce even a delay generated in processing of obtaining a transfer function for correcting distortion in digital coherent transmission. In the optical communication system according to the present invention, pilot data for estimating a transfer function for a transmission channel is transmitted through a transmission channel with a short transmission delay time, a transfer function of the transmission channel is estimated before receiving transmission data, and the transfer function is applied to other transmission channels.
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公开(公告)号：US20220120961A1
公开(公告)日：2022-04-21
申请号：US17422791
申请日：2020-01-06
Applicant: Nippon Telegraph and Telephone Corporation
Inventor： Takashi Matsui , Kazuhide Nakajima
Abstract: There are provided a multi-core optical fiber including four step-index type cores with a standard cladding diameter and having excellent mass productivity, quality, and yield while meeting desired specifications, and a design method thereof.
A multi-core optical fiber according to the present disclosure includes: four cores arranged in a square lattice shape along a longitudinal direction, each of the four cores having a step-index type refractive index distribution with a radius a; and a cladding region having a lower refractive index than that of each core and a diameter of 125±1 μm and provided on an outer peripheral portion of each core, where an absolute value of a relative refractive index difference between each core and the cladding region is Δ. The four cores are arranged so that a relationship between a minimum distance (OCT) from the center of each core to an outer periphery of the cladding region, a minimum value A of spacing between the cores, and the MFD at a wavelength of 1310 nm satisfies Formula C1, and the radius a of each core and the relative refractive index difference Δ between the core and the cladding region are set. [Formula C1] OCT≥3.73MFD+3.43 A≤−5.28MFD+83.54 (C1)-
公开(公告)号：US10816722B2
公开(公告)日：2020-10-27
申请号：US15556536
申请日：2016-03-18
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Takashi Matsui , Kyozo Tsujikawa , Fumihiko Yamamoto , Nobutomo Hanzawa
Abstract: An object is to provide a beam propagating method capable of satisfying desired output power and a desired propagation distance and a required condition of beam quality and a method of designing an optical fiber designing the structure of an optical fiber. According to the present invention, an effective core cross-sectional area Aeff is calculated based on desired specification values and, by appropriately adjusting the structure of an optical fiber satisfying the effective core cross-sectional area and the number of modes to be propagated, the structure of the optical fiber is determined. In this way, by controlling the excitation ratio of a high-order mode at the time of coupling laser light in the optical fiber designed as above, light of high-output laser can be propagated a long distance with the beam quality maintained.
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Patent Agency Ranking
公开(公告)号：US12189178B2
公开(公告)日：2025-01-07
申请号：US17928498
申请日：2020-06-03
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Yuto Sagae , Takashi Matsui , Kazuhide Nakajima
Abstract: The optical fiber according to the present invention includes, in a cross section of the optical fiber, one core region (11) and a cladding region (12) that is arranged on an outer periphery of the core region. The cladding region is a medium that has a lower refractive index than that of the core region and also has a smaller refractive index wavelength dispersion than that of the core region. The optical fiber has a solid core and therefore, allows more reduction in the Rayleigh scattering loss compared to an optical fiber having a hollow core. In addition, since the optical fiber adopts, for the cladding region, a medium that has a smaller refractive index wavelength dispersion than that of the core region, it allows a reduction in the wavelength dispersion of neff.
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公开(公告)号：US20250004214A1
公开(公告)日：2025-01-02
申请号：US18707816
申请日：2022-11-10
Applicant: Nippon Telegraph and Telephone Corporation
Inventor： Takahito KIRIHARA , Satoshi Narikawa , Katsuhisa TAGUCHI , Ayako IWAKI , Kazuhide Nakajima , Takashi Matsui , Chisato Fukai , Yuto SAGAE , Tomohiro TANIGUCHI , Hiroyuki IIDA
Abstract: An object of the present invention is to provide an optical transmission system capable of reducing system costs and reducing waste of output power of a light source. The optical transmission system according to the present invention includes an ultraviolet light source part 11a having a light emitting diode (LED) that outputs ultraviolet light, an optical transmission line 26 that propagates the ultraviolet light through a plurality of cores of a multi-core optical fiber or a plurality of cores of a bundle optical fiber obtained by bundling a plurality of single-core optical fibers, and an optical system 11c that narrows down a spot shape of the ultraviolet light output from the LED to a size including all of the plurality of cores in an optical axis direction, and causes the ultraviolet light to enter the plurality of cores.
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公开(公告)号：US12174413B2
公开(公告)日：2024-12-24
申请号：US18024559
申请日：2020-09-09
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Ryota Imada , Yoko Yamashita , Takashi Matsui , Taiji Sakamoto , Nobutomo Hanzawa , Noriyuki Araki , Shinichi Aozasa , Yuto Sagae , Kazuhide Nakajima
IPC: G02B6/02
Abstract: Provided are an LPFG and an optical transmission system in which a mode conversion amount does not depend on a polarization state and an electric field distribution. The LPFG according to the present invention includes cavity rows (25-1 and 25-2) of cavities 15 periodically arranged in a core region 11 of the few-mode fiber 10 at a position away from a central axis z of the core region 11 in parallel with the central axis z. Each of the cavity rows (25-1 and 25-2) is located at a different position in a longitudinal direction of the few-mode fiber 10 (where the position in a z direction is different), and the cavity rows (25-1 and 25-2) are located at positions shifted by 90° on a cross section of the core region 11 with the center of the cross section of the core region 11 (the intersection of an x-axis and a y-axis) as an origin.
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29.发明授权公开(公告)号：US11899237B2
公开(公告)日：2024-02-13
申请号：US17294892
申请日：2019-11-08
Applicant: Nippon Telegraph and Telephone Corporation
Inventor： Takashi Matsui , Kazuhide Nakajima
CPC classification number: G02B6/02042 , G02B27/0012
Abstract: It is an object of the present invention to provide a multicore optical fiber, a design method for the multicore optical fiber and an optical transmission method using the multicore optical fiber including four cores having a standard cladding diameter of 125±1 μm for an existing single mode optical fiber covering several thousands of kilometers of transmission. The multicore optical fiber according to the present invention disposes two-stage claddings with different refractive indices around each core, and designates as a predetermined range, a core radius a1, a radius a2 of a first cladding region surrounding each core, specific refractive index Δ1 relative to the core of the first cladding region and a specific refractive index Δ2 relative to the core of a second cladding region including four cores and the first cladding region.
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公开(公告)号：US10444428B2
公开(公告)日：2019-10-15
申请号：US15752809
申请日：2016-03-03
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Takashi Matsui , Kyozo Tsujikawa , Fumihiko Yamamoto , Nobutomo Hanzawa
Abstract: An optical fiber that is a photonic crystal fiber in which a plurality of holes is arranged along a longitudinal direction of the optical fiber, having a predetermined bending radius R determined according to a transmission distance L of the optical fiber and optical power output from the optical fiber, and having an inter-hole distance Λ and a ratio d/Λ between a hole diameter d and the inter-hole distance Λ such that light of a predetermined number of modes is transmitted and a bending loss of the light of a fundamental mode with the predetermined bending radius R is equal to or smaller than a predetermined value.
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