Patents by Inventor Kazuhide Nakajima

Kazuhide Nakajima has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20220365282
    Abstract: An object of the present invention is to provide a core position recognition method, a connection method, and a connection apparatus that can simplify connection operations, and reduce rotational displacement and positional displacement. The connection apparatus according to the present invention includes a function capable of acquiring the rotation amount of an MCF during the bonding/fixing step. Specifically, the connection apparatus of the present invention uses an MCF with lines drawn on a side surface thereof, thereby recognizing the rotation amount of the MCF from the side surface, and calculating the absolute positions of the cores. The connection apparatus according to the present invention can recognize the absolute position s of the cores from a side image of an MCF in a state in which the MCF has been rotated.
    Type: Application
    Filed: October 8, 2019
    Publication date: November 17, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Yoko YAMASHITA, Masaki WADA, Takashi MATSUI, Kazuhide NAKAJIMA
  • Publication number: 20220360358
    Abstract: An object of the present invention is to provide an optical transmission system capable of controlling a transmission capacity and a signal processing load of a MIMO equalizer, without depending on the number of propagation modes of the optical fiber.
    Type: Application
    Filed: September 17, 2019
    Publication date: November 10, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Taiji SAKAMOTO, Masaki WADA, Takashi YAMAMOTO, Kazuhide NAKAJIMA
  • Publication number: 20220344888
    Abstract: An objective of the present invention is to provide an amplification fiber having a cladding excitation configuration that improves amplification efficiency and an optical amplifier. An amplification fiber (10) according to the present invention is a multi-core amplification fiber having, from one end (E1) to the other end (EE), a plurality of cores (11b) in a cladding (11a), and a total distance from the one end (E1) to the other end (EE) in which rare earth ions are doped differs depending on the types of cores (11b). The cores (11b) are preferably disposed such that the cores of the same type are not adjacent to each other. By arranging the types of the cores in this manner, requirements for inter-core crosstalk can be mitigated since the bands of signal light in the adjacent cores are different. As a result, a density of cladding excitation light can be increased by shortening the inter-core distance, and thus the amplification efficiency can be improved.
    Type: Application
    Filed: September 26, 2019
    Publication date: October 27, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Shinichi AOZASA, Taiji SAKAMOTO, Kazuhide NAKAJIMA, Masaki WADA
  • Publication number: 20220334307
    Abstract: An object of the present invention is to provide an HAF having a structure in which the number of air holes is decreased to be smaller than that of a PCF and Rayleigh scattering loss may be more reduced than that in the existing HAF.
    Type: Application
    Filed: September 18, 2019
    Publication date: October 20, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Saki NOZOE, Nobutomo HANZAWA, Yuto SAGAE, Kazuhide NAKAJIMA, Kyozo TSUJIKAWA
  • Publication number: 20220337020
    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.
    Type: Application
    Filed: September 26, 2019
    Publication date: October 20, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Shinichi AOZASA, Taiji SAKAMOTO, Kazuhide NAKAJIMA, Masaki WADA
  • Publication number: 20220337016
    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.
    Type: Application
    Filed: September 26, 2019
    Publication date: October 20, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Shinichi AOZASA, Taiji SAKAMOTO, Kazuhide NAKAJIMA, Masaki WADA
  • Publication number: 20220337025
    Abstract: An objective of the present invention is to provide an optical amplifier having a cladding excitation configuration that improves amplification efficiency.
    Type: Application
    Filed: September 26, 2019
    Publication date: October 20, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Shinichi AOZASA, Taiji SAKAMOTO, Kazuhide NAKAJIMA, Masaki WADA
  • Patent number: 11474303
    Abstract: An object is to provide an optical fiber connector ferrule, a sleeve, and a method for manufacturing a ferrule member that can avoid an increase in manufacturing time and an increase in cost of optical connectors for connecting multicore optical fibers. The present invention provides an optical fiber connector ferrule, a sleeve, and a method for manufacturing ferrule member which realizes alignment of multicore optical fibers corresponding to the connection by mounting a ferrule on a multicore fiber and then cutting a ferrule member instead of aligning core positions by rotating an axis of an optical fiber and adjusting positions of cores to the ferrule, leading to simplification of a rotational alignment step.
    Type: Grant
    Filed: September 11, 2019
    Date of Patent: October 18, 2022
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Masaaki Takaya, Yoshiteru Abe, Ryo Koyama, Chisato Fukai, Kazunori Katayama, Kazuhide Nakajima, Yusuke Yamada
  • Publication number: 20220328301
    Abstract: In a mask pattern forming method, a resist film is formed over a thin film, the resist film is processed into resist patterns having a predetermined pitch by photolithography, slimming of the resist patterns is performed, and an oxide film is formed on the thin film and the resist patterns after an end of the slimming step in a film deposition apparatus by supplying a source gas and an oxygen radical or an oxygen-containing gas. In the mask pattern forming method, the slimming and the oxide film forming are continuously performed in the film deposition apparatus.
    Type: Application
    Filed: June 23, 2022
    Publication date: October 13, 2022
    Inventors: Kazuhide HASEBE, Shigeru NAKAJIMA, Jun OGAWA, Hiroki MURAKAMI
  • Patent number: 11454757
    Abstract: A planar waveguide having M×N number of cores and to which M number of fibers having N number of cores are connected. In the planar waveguide, in a connecting end surface of the planar waveguide to which the fibers are connected, P number of fibers having Q number of cores are connected, M×N is equal to P×Q, the planar waveguide includes a plurality of the cores arranged in a horizontal direction at the same height position in the planar waveguide, and a laminated structure having the cores at different positions in a height direction, so as to be aligned with the cores of the fibers connected to the connecting end surface, and the positions of the M×N number of cores are constant in the height direction, and change only in the horizontal direction.
    Type: Grant
    Filed: July 11, 2019
    Date of Patent: September 27, 2022
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Taiji Sakamoto, Yoshiteru Abe, Kazuhide Nakajima
  • Publication number: 20220294537
    Abstract: An object of the present invention is to provide an optical transmission system capable of easily controlling a transmission capacity and an optical signal quality even if a MIMO equalizer is provided. The optical transmission system according to the present invention is provided with an N×M MIMO equalizer, includes receivers (N units) equal in number to the spatial multiplexing order L of an optical fiber, and changes the number M of the signal beams of light transmitted through the optical fiber in the range of the spatial multiplex order L or less. The adjustment of the number M of signal beams of light makes it possible to adjust a transmission capacity and a signal quality of the optical transmission system even after construction of the transmission line.
    Type: Application
    Filed: August 23, 2019
    Publication date: September 15, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Taiji SAKAMOTO, Masaki WADA, Takashi YAMAMOTO, Kazuhide NAKAJIMA
  • Publication number: 20220294536
    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.
    Type: Application
    Filed: August 19, 2019
    Publication date: September 15, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Yuto SAGAE, Takashi MATSUI, Taiji SAKAMOTO, Kazuhide NAKAJIMA
  • Publication number: 20220276430
    Abstract: An object of the present invention is to provide a multi-core optical fiber that can prevent an increase in bending loss even when a distance between a peripheral core and a cladding boundary is decreased, and can improve a bending loss characteristic in a state where an influence on a cutoff wavelength and a mode field diameter is small, and a design method thereof.
    Type: Application
    Filed: July 21, 2020
    Publication date: September 1, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Taiji SAKAMOTO, Kazuhide NAKAJIMA, Takashi MATSUI, Kyozo TSUJIKAWA, Kunimasa SAITOH, Takeshi FUJISAWA
  • Patent number: 11404271
    Abstract: In a mask pattern forming method, a resist film is formed over a thin film, the resist film is processed into resist patterns having a predetermined pitch by photolithography, slimming of the resist patterns is performed, and an oxide film is formed on the thin film and the resist patterns after an end of the slimming step in a film deposition apparatus by supplying a source gas and an oxygen radical or an oxygen-containing gas. In the mask pattern forming method, the slimming and the oxide film forming are continuously performed in the film deposition apparatus.
    Type: Grant
    Filed: November 28, 2018
    Date of Patent: August 2, 2022
    Assignee: Tokyo Electron Limited
    Inventors: Kazuhide Hasebe, Shigeru Nakajima, Jun Ogawa, Hiroki Murakami
  • Patent number: 11404272
    Abstract: In a mask pattern forming method, a resist film is formed over a thin film, the resist film is processed into resist patterns having a predetermined pitch by photolithography, slimming of the resist patterns is performed, and an oxide film is formed on the thin film and the resist patterns after an end of the slimming step in a film deposition apparatus by supplying a source gas and an oxygen radical or an oxygen-containing gas. In the mask pattern forming method, the slimming and the oxide film forming are continuously performed in the film deposition apparatus.
    Type: Grant
    Filed: December 11, 2018
    Date of Patent: August 2, 2022
    Assignee: Tokyo Electron Limited
    Inventors: Kazuhide Hasebe, Shigeru Nakajima, Jun Ogawa, Hiroki Murakami
  • Publication number: 20220214496
    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 ? 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.
    Type: Application
    Filed: April 6, 2020
    Publication date: July 7, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Taiji SAKAMOTO, Kazuhide NAKAJIMA, Masaki WADA, Shinichi AOZASA, Takashi YAMAMOTO
  • Patent number: 11366266
    Abstract: An optical fiber includes a core, a first clad that is provided on an outer circumferential portion of the core and has a refractive index lower than that of the core, and a second clad that is provided on an outer circumferential portion of the first clad and has a refractive index lower than that of the first clad. In the optical fiber, a mode field diameter at a wavelength of 1.55 ?m is equal to or greater than 11.5 ?m, a cutoff wavelength is equal to or less than 1.53 ?m, a bending loss at a bending radius of 30 mm and a wavelength of 1.625 ?m is equal to or less than 2.0 dB/100 turns, and a delay time of transmission light per unit length at a wavelength of 1.55 ?m is equal to or less than 4.876 ?s/km.
    Type: Grant
    Filed: July 3, 2018
    Date of Patent: June 21, 2022
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Yuto Sagae, Kazuhide Nakajima, Takashi Matsui
  • Publication number: 20220170817
    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.
    Type: Application
    Filed: February 19, 2020
    Publication date: June 2, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Yuto SAGAE, Takashi MATSUI, Kyozo TSUJIKAWA, Kazuhide NAKAJIMA
  • Publication number: 20220120961
    Abstract: There are provided a multi-core optical fiber including four step-index type cores with a standard cladding diameter and having excellent mass productivity, quality, and yield while meeting desired specifications, and a design method thereof. A multi-core optical fiber according to the present disclosure includes: four cores arranged in a square lattice shape along a longitudinal direction, each of the four cores having a step-index type refractive index distribution with a radius a; and a cladding region having a lower refractive index than that of each core and a diameter of 125±1 ?m and provided on an outer peripheral portion of each core, where an absolute value of a relative refractive index difference between each core and the cladding region is ?.
    Type: Application
    Filed: January 6, 2020
    Publication date: April 21, 2022
    Inventors: Takashi Matsui, Kazuhide Nakajima
  • Patent number: 11237322
    Abstract: An optical fiber manufacturing method includes setting a first holding member and a rod inside a glass pipe, the first holding member made of glass and having plural holes formed, so that the rod is supported by the first holding member; filling glass particles between the rod and a glass pipe inner wall; holding the rod such that the rod and the filled glass particles are enclosed by the glass pipe inner wall and the first and second holding members, and sealing one end of the glass pipe and manufacturing an intermediate; and manufacturing an optical fiber from the intermediate, wherein a bulk density of the first and second holding members is set with reference to a bulk density of a filling portion made from the glass particles, and the predetermined range is determined according to a core diameter permissible variation range in its longitudinal direction.
    Type: Grant
    Filed: September 16, 2019
    Date of Patent: February 1, 2022
    Assignees: FURUKAWA ELECTRIC CO., LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Shinichi Arai, Harumi Inaba, Shigeto Matsumoto, Takeshi Yagi, Shinichi Aozasa, Kyozo Tsujikawa, Kazuhide Nakajima