公开(公告)号：US20240007189A1

公开(公告)日：2024-01-04

申请号：US18021991

申请日：2020-08-21

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

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

IPC: H04B10/291 ,  H04B10/25

CPC classification number: H04B10/2916 ,  H04B10/25 ,  G02B6/02042

Abstract: An object of the present invention is to provide an optical transmission system capable of satisfying XT required by a modulation system even if there is an inter-core loss difference in an MCF.
An optical transmission system of the present invention includes a multi-core optical fiber having a plurality of core regions and having different losses between at least two cores, a forward excitation light source and a multiplexing unit for allowing Raman amplification excitation light to be incident on each core of the multi-core optical fiber in the same direction as signal light, and a backward excitation light source and a multiplexing unit for allowing Raman amplification excitation light to be incident on each core of the multi-core optical fiber in a direction opposite to the signal light, wherein an intensity ratio of the forward excitation light to the backward excitation light is controlled (a ratio of power of excitation light is set to a predetermined value) such that crosstalk (XT) fluctuation between cores is reduced.

公开(公告)号：US20230390436A1

公开(公告)日：2023-12-07

申请号：US18032514

申请日：2020-10-21

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Tomohiro TANIGUCHI ,  Ayako IWAKI ,  Kazuhide NAKAJIMA ,  Nobutomo HANZAWA ,  Takashi MATSUI ,  Yuto SAGAE ,  Chisato FUKAI

IPC: A61L2/10

CPC classification number: A61L2/10 ,  A61L2202/11

Abstract: An object of the present invention is to provide an ultraviolet light irradiation system and an ultraviolet light irradiation method which are not limited in an ultraviolet light irradiation region and can be introduced economically. The present ultraviolet light irradiation system is a system configured to connect a single ultraviolet light source part and an irradiation part installed in the vicinity of an object place to be sterilized or the like by the optical cable formed by bundling a plurality of optical fibers (the single-core or the multi-core) or the multi-core optical fiber. Since the optical fiber is very thin and does not require power supply for transmitting the ultraviolet rays, even in a fine place where a person or a robot cannot enter, the ultraviolet light can be irradiated by laying the optical fiber or the optical cable.

公开(公告)号：US20230280525A1

公开(公告)日：2023-09-07

申请号：US18024074

申请日：2020-09-04

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

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

IPC: G02B6/028 ,  G02B6/02

CPC classification number: G02B6/0288 ,  G02B6/02042

Abstract: The present disclosure relates to a multi-core optical fiber including:
M (where M is a positive integer of 1 or larger) group(s) each consisting of N (where N is a positive integer of 2 or larger) core regions linearly arranged in a cross section; a cladding region that surrounds the plurality of core regions and has a refractive index lower than any of the plurality of core regions; and a coating region that surrounds the cladding region, wherein the plurality of core regions are arranged in line symmetry with respect to both imaginary lines orthogonal to each other at a center of the cladding region, a diameter of the cladding region is 180 μm or less, and a diameter of the coating region is 235 μm or more and 265 μm or less.

公开(公告)号：US20230163554A1

公开(公告)日：2023-05-25

申请号：US17913097

申请日：2020-03-30

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Shinichi AOZASA ,  Yoko YAMASHITA ,  Takashi MATSUI ,  Kazuhide NAKAJIMA ,  Taiji SAKAMOTO ,  Nobutomo HANZAWA ,  Noriyuki ARAKI ,  Ryota IMADA ,  Yuto SAGAE

IPC: H01S3/067 ,  G02B6/32 ,  G02B3/08

CPC classification number: H01S3/06754 ,  G02B3/08 ,  G02B6/32 ,  H01S3/1608

Abstract: An object of the present disclosure is to implement a clad-excitation rare-earth-added optical fiber amplifier with a high light-to-light conversion efficiency. The present disclosure is an optical fiber amplifier having, in a longitudinal direction of a rare-earth-added optical fiber, a light collection structure that collets an excitation light, which propagates through a clad portion, into a core portion.

公开(公告)号：US20220294536A1

公开(公告)日：2022-09-15

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

IPC: 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.

公开(公告)号：US20210234326A1

公开(公告)日：2021-07-29

申请号：US17266181

申请日：2019-08-06

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Yoko YAMASHITA ,  Masaki WADA ,  Takashi MATSUI ,  Kazuhide NAKAJIMA

IPC: H01S3/067 ,  G02B27/00

Abstract: Provided is a differential modal attenuation compensation fiber that has a simple structure and can reduce MDL while eliminating the need for precise alignment work, an optical amplifier, and a transmission line design method. The differential modal attenuation compensation fiber according to the present invention, imparts excess loss to a desired propagation mode by forming a cavity portion or a ring-shaped high refractive index portion in a core of an optical fiber. By forming the cavity portion or the ring-shaped high refractive index portion in a part of the profile of the core, electric field distribution of a particular mode propagating through the fiber can be controlled, and different losses can be imparted to different propagation modes at an interface between the cavity portion or the ring-shaped high refractive index portion and a region not including the cavity portion or the ring-shaped high refractive index portion.

公开(公告)号：US20190245317A1

公开(公告)日：2019-08-08

申请号：US16343357

申请日：2017-10-25

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Masaki WADA ,  Shinichi AOZASA ,  Taiji SAKAMOTO ,  Takashi YAMAMOTO ,  Kazuhide NAKAJIMA ,  Takayoshi MORI

IPC: H01S3/067 ,  H01S3/106 ,  H04B10/2581

CPC classification number: H01S3/06791 ,  H01S3/067 ,  H01S3/0675 ,  H01S3/06754 ,  H01S3/10 ,  H01S3/106 ,  H04B10/2581

Abstract: An optical amplifier of the present disclosure includes an optical resonator that includes an amplification fiber capable of amplifying signal light having one or more propagation modes and resonates at least one propagation mode of the signal light amplified by the amplification fiber; an excitation light source that outputs excitation light for exciting the amplification fiber; and a multiplexer that multiplexes the signal light and the excitation light, in which the optical resonator includes a gain clamp setting unit which sets gain clamp for at least one propagation mode out of a plurality of propagation modes resonating in the optical resonator.

公开(公告)号：US20190187365A1

公开(公告)日：2019-06-20

申请号：US16327946

申请日：2017-08-25

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Azusa URUSHIBARA ,  Takayoshi MORI ,  Taiji SAKAMOTO ,  Masaki WADA ,  Takashi YAMAMOTO ,  Kazuhide NAKAJIMA

IPC: G02B6/02 ,  G02B6/14 ,  G02B6/44 ,  H04B10/2581

Abstract: An optical transmission system according to the present disclosure is a mode multiplexed optical transmission system using a multi-mode optical fiber in which a plurality of propagation modes propagate as a transmission line, the optical transmission system including an optical fiber transmission line (83) that includes an optical fiber with two or more propagation modes; and a plurality of mode converters (91) that are configured to generate mode coupling between at least one pair of the propagation modes, in which a variation in an installation interval of the plurality of mode converters (91) is equal to or less than a threshold value determined by the transmission line length (Lt) of the optical fiber transmission line (83).

公开(公告)号：US20250093575A1

公开(公告)日：2025-03-20

申请号：US18294124

申请日：2021-08-04

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

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

IPC: G02B6/02

Abstract: An object of the present disclosure is to provide an optical fiber having a simple structure, as well as attaining removal of loss components generated in an electric field part oozing out to a core-clad interface or a clad region and reduction in scattering loss generated from an interface with the clad region.
The present disclosure relates to an optical fiber including a core for propagating light, a cladding disposed around the core, an air layer between the core and the cladding, and two or more bridges for supporting the core in the air layer.

公开(公告)号：US20250076568A1

公开(公告)日：2025-03-06

申请号：US18293918

申请日：2021-08-02

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Nobutomo HANZAWA ,  Takayoshi MORI ,  Takashi MATSUI ,  Yoko YAMASHITA ,  Kazuhide NAKAJIMA

IPC: G02B6/02

Abstract: The present disclosure is a photonic crystal fiber in which a plurality of holes are formed in a cladding, having a uniform light refractive index, capable of propagating three modes of a fundamental mode, a first higher-order mode, and a second higher-order mode, wherein the plurality of holes are disposed in a triangular lattice pattern so as to surround a center of the photonic crystal fiber with no hole disposed at the center of the photonic crystal fiber, and the photonic crystal fiber has a ratio d/A of a diameter d of each of the holes to a pitch A between the holes such that a confinement loss of a third higher-order mode at a minimum wavelength within a used wavelength range is 1.0 dB/m or more and a confinement loss at a maximum wavelength is 0.001 dB/km or less.