公开(公告)号：US20240142696A1

公开(公告)日：2024-05-02

申请号：US18277320

申请日：2021-02-17

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

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

IPC: G02B6/02 ,  G02B27/00

CPC classification number: G02B6/02095 ,  G02B27/0012

Abstract: An objective of the present invention is to provide a mode conversion device capable of designing any coupling efficiency and full width at half maximum, and a design method therefor.
According to the present invention, a mode conversion device includes a long period grating at a core of an optical fiber through which light is able to propagate in at least two propagation modes. The long period grating satisfies a relationship of Expression C1, where a full width at half maximum FWHM is a wavelength band in which the coupling efficiency is a half of coupling efficiency of mode conversion at a center wavelength, C is coupling efficiency, Lc is a complete coupling length, Lg is a grating length, Λ is a grating pitch, and Δβ is a propagation constant difference between the two propagation modes at the center wavelength of a mode conversion target.







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公开(公告)号：US20200225407A1

公开(公告)日：2020-07-16

申请号：US16633424

申请日：2018-07-31

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

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

IPC: G02B6/02 ,  H01S3/10 ,  H04B10/2581

Abstract: The optical fiber of the present invention includes a core, and a cladding that is provided on an outer periphery of the core and has a refractive index lower than a refractive index of the core region. In the optical fiber of the present invention, a V value representing a normalized frequency of an LP02 mode is greater than or equal to 4.8 and less than or equal to 6.4.

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：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.

公开(公告)号：US20190386748A1

公开(公告)日：2019-12-19

申请号：US16312051

申请日：2017-07-04

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

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

IPC: H04B10/2581 ,  G02B6/02 ,  H04B10/50 ,  H04B10/60

Abstract: The optical fiber according to the present disclosure is an optical fiber having a pure silica core which is a step index core through which an LPm1 mode with an effective area of 250 μm2 or more is propagated by setting a relative refractive index difference to 0.60% or less, considering an effective cutoff condition, and only 2 or more modes or the LPm1 mode are propagated, with the optical fiber as the transmission line.

公开(公告)号：US20240427084A1

公开(公告)日：2024-12-26

申请号：US18701805

申请日：2021-10-28

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

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

IPC: G02B6/14

Abstract: The present disclosure aims to provide a short optical fiber-type mode converter having small wavelength dependency.
The present disclosure is about a mode converter including a cladding having a constant refractive index, a core having a refractive index higher than the refractive index of the cladding in the cladding, and a refractive index modulation part provided to obliquely cross the core and having a different refractive index from a refractive index of surroundings.

公开(公告)号：US20240369769A1

公开(公告)日：2024-11-07

申请号：US18573170

申请日：2021-06-28

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

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

IPC: G02B6/293 ,  G02B6/02

Abstract: An object of the present disclosure is to provide an optical side input/output circuit for allowing light for being input into or output from a side surface of an optical fiber with high efficiency.
The present disclosure is an optical side input/output circuit including: a tap unit in which a tap waveguide is formed for allowing light for propagation through a core of an optical fiber for being input into or output from a side surface of the optical fiber; and a refractive index matching unit, having a refractive index higher than a refractive index of the tap waveguide, on the side surface of the optical fiber where the light is allowed for being input or output by the tap waveguide.

公开(公告)号：US20170160466A1

公开(公告)日：2017-06-08

申请号：US15440228

申请日：2017-02-23

Applicant: FURUKAWA ELECTRIC CO., LTD. ,  NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Katsunori IMAMURA ,  Tomohiro GONDA ,  Ryuichi SUGIZAKI ,  Taiji SAKAMOTO ,  Takayoshi MORI ,  Masaki WADA ,  Takashi YAMAMOTO ,  Fumihiko YAMAMOTO

IPC: G02B6/02 ,  C03B37/16 ,  C03B37/012 ,  G02B6/028

CPC classification number: G02B6/02042 ,  C03B37/01205 ,  C03B37/01222 ,  C03B37/027 ,  C03B37/16 ,  C03B2203/10 ,  C03B2203/18 ,  C03B2203/22 ,  C03B2203/23 ,  C03B2203/26 ,  C03B2203/34 ,  C03B2205/30 ,  G02B6/0288 ,  G02B6/0365

Abstract: A multicore fiber includes a plurality of unit multicore fibers each including: a plurality of core portions; and a clad portion which is formed in an outer circumference of the core portions and has a refractive index lower than a maximum refractive index of the core portions. The plurality of the core portions have substantially same refractive index profile and different group delays at same wavelength in same propagation mode. The core portions of the multicore fiber are configured so that the core portions of the plurality of the unit multicore fibers are connected in cascade, a maximum value of differential group delays between the core portions of the multicore fiber is smaller than a reduced value of a maximum value of differential group delays between the core portions of each unit multicore fiber as a value in terms of a length of the multicore fiber.

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).