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    MULTI-CORE OPTICAL FIBER AND DESIGN METHOD
    31.
    发明公开
    MULTI-CORE OPTICAL FIBER AND DESIGN METHOD 审中-公开

    公开(公告)号：US20230341618A1

    公开(公告)日：2023-10-26

    申请号：US18020539

    申请日：2020-08-12

    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

    Inventor： Takashi MATSUI ,  Kazuhide NAKAJIMA ,  Taiji SAKAMOTO ,  Yuto SAGAE

    IPC: G02B27/00 ,  G02B6/02

    CPC classification number: G02B6/02042 ,  G02B6/02028 ,  G02B27/0012

    Abstract: The present invention is to provide a multi-core optical fiber that can expand its transmission wavelength band, and extend its transmission distance by reducing crosstalk, and also provide a method for designing the multi-core optical fiber. A multi-core optical fiber according to the present invention includes: four cores that are arranged in a square lattice pattern in a longitudinal direction; and a cladding region that is formed around the outer peripheral portions of the cores and has a lower refractive index than the cores, the absolute value of the relative refractive index difference between the cores and the cladding region being represented by Δ. In the multi-core optical fiber, the diameter of the cladding region is 125 ± 1 µm, the cutoff wavelength is 1.45 µm or shorter, the mode field diameter MFD at a wavelength of 1.55 µm is 9.5 to 10.0 µm, the bending loss at a wavelength of 1.625 µm and with a bending radius of 30 mm is 0.1 dB/100 turns or smaller, and the inter-core crosstalk at the wavelength of 1.625 µm is -47 dB/km or smaller.

    OPTICAL FIBER
    32.
    发明公开
    OPTICAL FIBER 审中-公开

    公开(公告)号：US20230244028A1

    公开(公告)日：2023-08-03

    申请号：US17928498

    申请日：2020-06-03

    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

    Inventor： Yuto SAGAE ,  Takashi MATSUI ,  Kazuhide NAKAJIMA

    IPC: G02B6/036 ,  G02B6/028 ,  G02B6/02

    CPC classification number: G02B6/03622 ,  G02B6/0281 ,  G02B6/02366

    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.

    OPTICAL FIBER EVALUATION DEVICE AND OPTICAL FIBER EVALUATION METHOD
    33.
    发明公开
    OPTICAL FIBER EVALUATION DEVICE AND OPTICAL FIBER EVALUATION METHOD 审中-公开

    公开(公告)号：US20230221487A1

    公开(公告)日：2023-07-13

    申请号：US18009784

    申请日：2020-06-24

    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

    Inventor： Nobutomo HANZAWA ,  Takashi MATSUI ,  Yuto SAGAE ,  Kazuhide NAKAJIMA

    IPC: G02B6/02

    CPC classification number: G02B6/02042 ,  G02B6/02342

    Abstract: The purpose of the present invention is to provide an optical fiber evaluation equipment and an optical fiber evaluation method that evaluate the center of a cladding of an MCF and a deviation of the center of each core of the MCF from a design value with ease and high accuracy.
    The optical fiber evaluation equipment according to the present invention approximates the outside diameter of a cladding by a circle, based on a cross-sectional image of an MCF, and determines the center of the circle as the center of the cladding. In addition, the optical fiber evaluation equipment according to the present invention obtains the center coordinates of cores with an origin at the center of the circle, rotates the cross-sectional image so as to minimize a difference between the center coordinates and design coordinates of each core, and derives the minimum value thereof as the amount of deviation of the center of each core.

    ACOUSTIC MODE PROPAGATION SPEED MEASUREMENT METHOD AND ACOUSTIC MODE PROPAGATION SPEED MEASUREMENT DEVICE
    34.
    发明申请
    ACOUSTIC MODE PROPAGATION SPEED MEASUREMENT METHOD AND ACOUSTIC MODE PROPAGATION SPEED MEASUREMENT DEVICE 有权

    公开(公告)号：US20220170817A1

    公开(公告)日：2022-06-02

    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

    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.

    PHOTONIC CRYSTAL FIBER AND HIGH-POWER LIGHT TRANSMISSION SYSTEM
    36.
    发明申请
    PHOTONIC CRYSTAL FIBER AND HIGH-POWER LIGHT TRANSMISSION SYSTEM 审中-公开

    公开(公告)号：US20190339513A1

    公开(公告)日：2019-11-07

    申请号：US16507570

    申请日：2019-07-10

    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

    Inventor： Takashi MATSUI ,  Kazuhide NAKAJIMA ,  Kyozo TSUJIKAWA ,  Fumihiko YAMAMOTO

    IPC: G02B27/00 ,  G02B6/02 ,  G02B6/032 ,  G02B6/42

    Abstract: A photonic crystal fiber according to the present invention has a plurality of holes arranged in the optical fiber along a longitudinal direction, in which the holes are arranged such that, in a cross section, a hole ratio which is an area of the holes per unit area is larger in a central side than in an outer side in a portion corresponding to a cladding and that a wide core area can be obtained while the number of modes that can be propagated is limited to several. Moreover, in a high-power optical transmission system according to the present invention, the amount of axis misalignment between the central axis of a laser oscillator and the central axis of the photonic crystal fiber is less than or equal to a certain amount.

    ALIGNMENT APPARATUS AND ALIGNMENT METHOD
    38.
    发明申请
    ALIGNMENT APPARATUS AND ALIGNMENT METHOD 审中-公开

    公开(公告)号：US20180372954A1

    公开(公告)日：2018-12-27

    申请号：US16062034

    申请日：2016-12-27

    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

    Inventor： Takashi MATSUI ,  Kazuhide NAKAJIMA ,  Taiji SAKAMOTO ,  Koutaro SAITO

    IPC: G02B6/255 ,  G01B11/27 ,  G02B6/42 ,  G02B6/38

    Abstract: An alignment apparatus that can efficiently align an optical fiber, and an alignment method will be provided.According to the embodiments, the alignment apparatus that aligns an optical fiber comprises an acquisition unit, a calculation unit, and a rotation processing unit. The acquisition unit acquires one or more side images of the optical fiber. The calculation unit calculates correlation coefficients between the luminances of the one or more side images and those of one or more reference side images. The rotation processing unit rotates the optical fiber in the axis direction of the optical fiber so that the correlation coefficients peak.

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