公开(公告)号：US20230336338A1

公开(公告)日：2023-10-19

申请号：US18009399

申请日：2020-06-11

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

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

IPC: H04L9/08 ,  H04B10/25

CPC classification number: H04L9/088 ,  H04B10/25

Abstract: It is an object of the present disclosure to reduce the risk of information exploitation by a malicious third party while allowing communication data to be demodulated in real time. An optical transmission system according to the present disclosure includes a transmitter which transmits an optical signal representing a cryptographic key and an optical signal representing communication data individually, an optical transmission path including a heterogeneous multi-core optical fiber having multiple cores, at least one of which has a different propagation delay time, the optical transmission path transmitting the optical signal representing the cryptographic key using a first core with a smaller delay among the multiple cores and the optical signal representing the communication data using a second core with a greater delay than the first core, and a receiver which individually receives the optical signals representing the cryptographic key and the communication data output from the individual cores of the optical transmission path and demodulates the received communication data on the basis of the received cryptographic key information.

公开(公告)号：US20250118941A1

公开(公告)日：2025-04-10

申请号：US18832029

申请日：2022-02-03

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Ryota IMADA ,  Taiji SAKAMOTO ,  Shinichi AOZASA ,  Kazuhide NAKAJIMA

IPC: H01S3/067 ,  H01S3/10 ,  H01S3/16

Abstract: An optical amplifier of the present disclosure includes a rare-earth doped fiber including a plurality of cores, in which a v value of the plurality of cores of the rare-earth doped fiber is less than 2.405, the plurality of cores has a core pitch of a normalized coupling coefficient of 1.0×10−3 or more, and on injection of excitation light into a clad part of the rare-earth doped fiber in a state of being bent at a predetermined bending radius, propagating light in the rare-earth doped fiber is amplified with mode-dependent gain characteristics dependent on the bending radius.

公开(公告)号：US20230324604A1

公开(公告)日：2023-10-12

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

CPC classification number: G02B6/02095

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.

公开(公告)号：US20250141174A1

公开(公告)日：2025-05-01

申请号：US18836969

申请日：2022-02-17

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Taiji SAKAMOTO ,  Ryota IMADA ,  Shinichi AOZASA ,  Kazuhide NAKAJIMA

IPC: H01S3/094 ,  H01S3/067

Abstract: The present disclosure is an optical fiber amplifier including: an amplification optical fiber doped with a rare earth element, in which a pump light combiner for injecting multimode pump light into a cladding region of the amplification optical fiber is connected to an input end or an output end of the amplification optical fiber, and a reflective device for reflecting the pump light and transmitting signal light is connected to an end part, of the amplification optical fiber, to which the pump light combiner is not connected.

公开(公告)号：US20250105578A1

公开(公告)日：2025-03-27

申请号：US18833531

申请日：2022-02-17

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Taiji SAKAMOTO ,  Ryota IMADA ,  Shinichi AOZASA ,  Kazuhide NAKAJIMA

IPC: H01S3/067 ,  H01S3/094

Abstract: An amplification optical fiber according to the present disclosure is an amplification optical fiber doped with a rare earth element, the amplification optical fiber including: a first cladding enclosing cores of the amplification optical fiber; and a second cladding enclosing the first cladding, in which the two or more cores are disposed inside the first cladding in a cross section of the amplification optical fiber, and a core cladding ratio Rcc, which is a ratio of a sum of areas of the two or more cores to a sum of areas of the two or more cores and the first cladding in the cross section of the amplification optical fiber, is 0.0095

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：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.