公开(公告)号：US20190196106A1

公开(公告)日：2019-06-27

申请号：US16322432

申请日：2017-08-01

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

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

IPC: G02B6/26 ,  G02B6/036 ,  G02B6/02

Abstract: A differential mode attenuation compensator includes a first multi-mode optical fiber and a third multi-mode optical fiber in which a plurality of propagation modes propagate in a wavelength of a propagating optical signal; and a second multi-mode optical fiber including a core and a clad and arranged with a central axis aligned between the first multi-mode optical fiber and the third multi-mode optical fiber, in which each loss in the plurality of propagation modes is different in the first multi-mode optical fiber and the third multi-mode optical fiber.

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：US20220214496A1

公开(公告)日：2022-07-07

申请号：US17605758

申请日：2020-04-06

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

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

IPC: G02B6/02 ,  G02B27/00

Abstract: An object is to provide a multi-core configuration for acquiring a random mode coupling in a case of an arbitrary core refractive index.
A multi-core optical fiber according to the present invention is an optical fiber in which two or more core regions are arranged in a clad region having a refractive index at a minimum core interval Λ smaller than a refractive index of the cores, a configuration of the cores is that including one propagation mode, and the core configuration and the core interval are adjusted so that an inter-mode coupling coefficient between adjacent cores is within a range from 0.73 to 120 m−1.

公开(公告)号：US20220337025A1

公开(公告)日：2022-10-20

申请号：US17762399

申请日：2019-09-26

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Shinichi AOZASA ,  Taiji SAKAMOTO ,  Kazuhide NAKAJIMA ,  Masaki WADA

IPC: H01S3/23 ,  H01S3/067

Abstract: An objective of the present invention is to provide an optical amplifier having a cladding excitation configuration that improves amplification efficiency. The optical amplifier includes an optical amplification unit 36 in which n (n is a natural number equal to or greater than 2) amplification fibers 34 that optically amplify signal light propagating through cores with excitation light supplied to claddings and n−1 optical input/output units 35 that input/output the signal light to/from the cores and the outside of the amplification fibers 34 are connected in series such that the amplification fibers 34 and the optical input/output units 35 are disposed in an alternating manner, an excitation light generator 31 that outputs the excitation light in multi-mode, and optical multiplexer/demultiplexers 33 that cause the excitation light from the excitation light generator 31 that has been divided into two light beams to be incident on the claddings of the amplification fibers 34 disposed at both ends of the optical amplification unit 36 and cause the signal light to be input to/output from the cores of the amplification fibers 34 disposed at both ends of the optical amplification unit 36.

公开(公告)号：US20220337020A1

公开(公告)日：2022-10-20

申请号：US17760713

申请日：2019-09-26

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Shinichi AOZASA ,  Taiji SAKAMOTO ,  Kazuhide NAKAJIMA ,  Masaki WADA

IPC: H01S3/094 ,  H01S3/067 ,  H01S3/16

Abstract: An object is to provide an optical amplifier with a cladding pumped configuration that improves amplification efficiency. The optical amplifier according to the present invention includes a pump light conversion fiber 11 that converts first pump light L1 with a first wavelength propagating in a cladding into second pump light L2 with a second wavelength, an amplification fiber 13 that is connected to the pump light conversion fiber 11 and optically amplifies signal light Ls with the second pump light L2 supplied to the cladding from the pump light conversion fiber 11, and an oscillator 12 that causes the second pump light L2 to be reflected on two reflectors 15 and to reciprocate within the claddings of the pump light conversion fiber 11 and the amplification fiber 13 to cause laser oscillation of the second pump light L2.

公开(公告)号：US20220337016A1

公开(公告)日：2022-10-20

申请号：US17760697

申请日：2019-09-26

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Shinichi AOZASA ,  Taiji SAKAMOTO ,  Kazuhide NAKAJIMA ,  Masaki WADA

IPC: H01S3/067

Abstract: An objective is to provide an optical amplifier having a core excitation configuration that improves amplification efficiency. An optical amplifier according to the present invention includes an excitation light conversion fiber 11 that absorbs first excitation light L1 propagating in a cladding and having a first wavelength and emits, into a core, spontaneous emission light having a second wavelength, an oscillator 12 for causing the spontaneous emission light to be reflected on two reflectors 15 to reciprocate the light within the core of the excitation light conversion fiber 11 and laser-oscillating second excitation light L2 having the second wavelength, and an amplification fiber 13 that is connected to the excitation light conversion fiber 11 and amplifies signal light with the second excitation light L2 supplied from the excitation light conversion fiber 11 to the core.

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：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：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：US20240072507A1

公开(公告)日：2024-02-29

申请号：US18269611

申请日：2021-01-21

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Shinichi AOZASA ,  Taiji SAKAMOTO ,  Kazuhide NAKAJIMA ,  Takashi MATSUI

IPC: H01S3/10 ,  F21V8/00

CPC classification number: H01S3/10023 ,  G02B6/0003

Abstract: The purpose of the present invention is to provide an optical fiber amplifier capable of seamlessly and collectively amplifying optical signals in a plurality of bands.
In order to achieve the aforementioned purpose, the optical fiber amplifier according to the present invention is the optical fiber amplifier that amplifies multiple wavelength bands, and in cross-section, one signal light primary propagation region, and a doped region where rare-earth ions have been added, wherein the doped region includes the rare-earth-doped optical fiber existing other than the propagation region. The optical fiber amplifier uses the fact that the main propagation regions of the signal light are made the same in the fiber cross-section of the rare-earth-doped optical fiber and the propagation regions of the signal light are partially different in the signal wavelength, and adds rare-earth ions to the partially different propagation regions to make amplification factors different for each signal wavelength and flatten the gain of each amplification wavelength band.