Patents by Inventor Toshio Kurashima
Toshio Kurashima 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).
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Patent number: 9562827Abstract: A measuring method of a longitudinal distribution of bending loss of an optical fiber includes calculating an arithmetical mean value I(x) from two backscattering light intensities of two backscattering light at a position x obtained by bidirectional OTDR measurement of the optical fiber; and obtaining a bending loss value at the position x from a mode field diameter 2W(x) and a relative refractive index difference ?(x) at the position x calculated from the arithmetical mean value.Type: GrantFiled: August 19, 2011Date of Patent: February 7, 2017Assignees: FUJIKURA LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Shoji Tanigawa, Itaru Ishida, Shoichiro Matsuo, Toshio Kurashima, Kazuhide Nakajima, Tomoya Shimizu, Takashi Matsui, Yukihiro Goto
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Patent number: 9175946Abstract: A measuring method of a hole diameter of a holey optical fiber includes calculating an arithmetical mean value I(x) from two backscattering light intensities at a position x of two backscattering light waveforms of the holey optical fiber, in which the two backscattering light waveforms are obtained by OTDR measurement; and obtaining the hole diameter at the position x, based on a correlation between an arithmetical mean value I(x) and an hole diameter of the holey optical fiber that is obtained in advance.Type: GrantFiled: August 19, 2011Date of Patent: November 3, 2015Assignees: NIPPON TELEGRAPH AND TELEPHONE CORPORATION, FUJIKURA LTD.Inventors: Itaru Ishida, Shoji Tanigawa, Shoichiro Matsuo, Toshio Kurashima, Kazuhide Nakajima, Tomoya Shimizu, Takashi Matsui, Yukihiro Goto
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Patent number: 9075185Abstract: A hole-assisted optical fiber includes a core portion and a cladding portion that includes an inner cladding layer, an outer cladding layer, and holes formed around the core portion. A diameter of the core portion is 3 ?m to 9.8 ?m, a relative refractive index difference of the core portion relative to the outer cladding layer is 0.11% to 0.45%, an outside diameter of the inner cladding layer is 53 ?m or less, a relative refractive index difference of the inner cladding layer relative to the outer cladding layer is a negative value, ?0.30% or more, a diameter of each hole is 2.4 ?m to 4.0 ?m, a hole occupancy rate is 17% to 48%, a bending loss at a wavelength of 1625 nm when bent at a radius of 5 mm is 1 dB/turn or less, and a cut-off wavelength is 1550 nm or less.Type: GrantFiled: January 31, 2013Date of Patent: July 7, 2015Assignees: FURUKAWA ELECTRIC CO., LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Naomi Kumano, Iwao Shimotakahara, Ryuichi Sugizaki, Takeshi Yagi, Tomoya Shimizu, Takashi Matsui, Yukihiro Goto, Toshio Kurashima, Kazuhide Nakajima
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Patent number: 8800323Abstract: An optical fiber which, at an optical fiber connecting end having a plurality of voids around the periphery of a core, has a light-permeable substance, such as a resin or glass whose refractive index is lower than that of quartz type substances, filled in the voids adjacent to the connecting end. An optical fiber connecting section where an optical fiber having a plurality of voids in a clad around the periphery of a core is connected to another optical fiber, wherein the optical fiber is connected end-to-end to aforesaid another optical fiber through a refractive index matching agent whose refractive index at the minimum temperature in actual use is lower than that of the core.Type: GrantFiled: March 5, 2008Date of Patent: August 12, 2014Assignees: Hitachi Metals, Ltd., Nippon Telegraph and Telephone CorporationInventors: Yoshinori Kurosawa, Bing Yao, Kazumasa Ohsono, Masao Tachikura, Hisanori Nakai, Toshio Kurashima, Eiji Araki, Katumi Hiramatu
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Patent number: 8702317Abstract: An optical connector having an optical fiber inserted into a connector main body includes a buckling regulating section whose length in an optical fiber insertion direction is formed variable and which regulates a buckling of the optical fiber while becoming short in an optical fiber insertion direction when the optical fiber is inserted into the connector main body. Even if an insertion area is made long, since no buckling of the optical fiber is generated, the buckling regulating section can sufficiently increase an insertion force of the optical fiber. Thus, even when foreign substances such as dusts enter and an insertion resistance increases, the optical fiber can be securely inserted. Further, the buckling regulating section is very advantageous to realize an end surface preparation of the optical fiber making use of the insertion force of the optical fiber such as a coating removing of the optical fiber, and an end surface grinding preparation of the optical fiber.Type: GrantFiled: August 6, 2010Date of Patent: April 22, 2014Assignee: Nippon Telegraph and Telephone CorporationInventors: Ryo Koyama, Kazuhide Nakajima, Masaaki Takaya, Toshio Kurashima, Masatoshi Shimizu, Kyoichi Nakamizo
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Publication number: 20120128303Abstract: An optical connector having an optical fiber inserted into a connector main body includes a buckling regulating section whose length in an optical fiber insertion direction is formed variable and which regulates a buckling of the optical fiber while becoming short in an optical fiber insertion direction when the optical fiber is inserted into the connector main body. Even if an insertion area is made long, since no buckling of the optical fiber is generated, the buckling regulating section can sufficiently increase an insertion force of the optical fiber. Thus, even when foreign substances such as dusts enter and an insertion resistance increases, the optical fiber can be securely inserted. Further, the buckling regulating section is very advantageous to realize an end surface preparation of the optical fiber making use of the insertion force of the optical fiber such as a coating removing of the optical fiber, and an end surface grinding preparation of the optical fiber.Type: ApplicationFiled: August 6, 2010Publication date: May 24, 2012Inventors: Ryo Koyama, Kazuhide Nakajima, Masaaki Takaya, Toshio Kurashima, Masatoshi Shimizu, Kyoichi Nakamizo
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Patent number: 8181487Abstract: An optical fiber preform manufacturing method includes: supporting a drilling jig in a radial direction of a preform that is cylinder-shaped; moving the drilling jig in a longitudinal direction of the preform; and forming a plurality of slits each extending in the longitudinal direction and each directed from an outer side of the preform toward a center the preform, and a plurality of holes each extending in the longitudinal direction and each connecting with an end of one of the plurality of slits in a depth direction of the one of the plurality of slits.Type: GrantFiled: September 3, 2010Date of Patent: May 22, 2012Assignees: Furukawa Electric Co., Ltd., Nippon Telegraph and Telephone CorporationInventors: Ryuichi Sugizaki, Naomi Kumano, Iwao Shimotakahara, Harumi Inaba, Takeshi Yagi, Tomoya Shimizu, Toshio Kurashima, Kazuhide Nakajima
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Publication number: 20120044482Abstract: A measuring method of a hole diameter of a holey optical fiber includes calculating an arithmetical mean value I(x) from two backscattering light intensities at a position x of two backscattering light waveforms of the holey optical fiber, in which the two backscattering light waveforms are obtained by OTDR measurement; and obtaining the hole diameter at the position x, based on a correlation between an arithmetical mean value I(x) and an hole diameter of the holey optical fiber that is obtained in advance.Type: ApplicationFiled: August 19, 2011Publication date: February 23, 2012Applicants: NIPPON TELEGRAPH AND TELEPHONE CORPORATION, FUJIKURA LTD.Inventors: Itaru ISHIDA, Shoji TANIGAWA, Shoichiro MATSUO, Toshio KURASHIMA, Kazuhide NAKAJIMA, Tomoya SHIMIZU, Takashi MATSUI, Yukihiro GOTO
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Publication number: 20120042696Abstract: A measuring method of a longitudinal distribution of bending loss of an optical fiber includes calculating an arithmetical mean value I(x) from two backscattering light intensities of two backscattering light at a position x obtained by bidirectional OTDR measurement of the optical fiber; and obtaining a bending loss value at the position x from a mode field diameter 2W(x) and a relative refractive index difference ?(x) at the position x calculated from the arithmetical mean value.Type: ApplicationFiled: August 19, 2011Publication date: February 23, 2012Applicants: NIPPON TELEGRAPH AND TELEPHONE CORPORATION, FUJIKURA LTD.Inventors: Shoji TANIGAWA, Itaru ISHIDA, Shoichiro MATSUO, Toshio KURASHIMA, Kazuhide NAKAJIMA, Tomoya SHIMIZU, Takashi MATSUI, Yukihiro GOTO
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Publication number: 20110141458Abstract: A coated optical fiber identifying apparatus is provided, which can realize coated optical fiber identification for a single mode optical fiber with holes. The coated optical fiber identifying apparatus comprises a grating forming tool 20 for forming a grating by applying a force to an optical fiber with a plurality of protrusions 23, and a photo detector 30 for detecting leak light generated in the optical fiber 1, wherein the plurality of the protrusions 23 are arranged in a period ? within a range of 0.24 mm to 0.75 mm.Type: ApplicationFiled: June 30, 2009Publication date: June 16, 2011Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takashi Matsui, Kunihiro Toge, Toshio Kurashima, Shigeru Tomita
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Publication number: 20100326139Abstract: An optical fiber preform manufacturing method includes: supporting a drilling jig in a radial direction of a preform that is cylinder-shaped; moving the drilling jig in a longitudinal direction of the preform; and forming a plurality of slits each extending in the longitudinal direction and each directed from an outer side of the preform toward a center the preform, and a plurality of holes each extending in the longitudinal direction and each connecting with an end of one of the plurality of slits in a depth direction of the one of the plurality of slits.Type: ApplicationFiled: September 3, 2010Publication date: December 30, 2010Applicants: FURUKAWA ELECTRIC CO., LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Ryuichi SUGIZAKI, Naomi Kumano, Iwao Shimotakahara, Harumi Inaba, Takeshi Yagi, Tomoya Shimizu, Toshio Kurashima, Kazuhide Nakajima
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Patent number: 7658550Abstract: An optical fiber which, at an optical fiber connecting end having a plurality of voids around the periphery of a core, has a light-permeable substance, such as a resin or glass whose refractive index is lower than that of quartz type substances, filled in the voids adjacent to the connecting end. An optical fiber connecting section where an optical fiber having a plurality of voids in a clad around the periphery of a core is connected to another optical fiber, wherein the optical fiber is connected end-to-end to aforesaid another optical fiber through a refractive index matching agent whose refractive index at the minimum temperature in actual use is lower than that of the core.Type: GrantFiled: March 5, 2008Date of Patent: February 9, 2010Assignees: Hitachi Cable Ltd., Nippon Telegraph and Telephone CorporationInventors: Yoshinori Kurosawa, Bing Yao, Kazumasa Ohsono, Masao Tachikura, Hisanori Nakai, Toshio Kurashima, Eiji Araki, Katumi Hiramatu
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Publication number: 20080253726Abstract: An optical fiber which, at an optical fiber connecting end having a plurality of voids around the periphery of a core, has a light-permeable substance, such as a resin or glass whose refractive index is lower than that of quartz type substances, filled in the voids adjacent to the connecting end. An optical fiber connecting section where an optical fiber having a plurality of voids in a clad around the periphery of a core is connected to another optical fiber, wherein the optical fiber is connected end-to-end to aforesaid another optical fiber through a refractive index matching agent whose refractive index at the minimum temperature in actual use is lower than that of the core.Type: ApplicationFiled: March 5, 2008Publication date: October 16, 2008Applicants: HITACHI CABLE, LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Yoshinori Kurosawa, Bing Yao, Kazumasa Ohsono, Masao Tachikura, Hisanori Nakai, Toshio Kurashima, Eiji Araki, Katumi Hiramatu
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Publication number: 20080250816Abstract: An optical fiber which, at an optical fiber connecting end having a plurality of voids around the periphery of a core, has a light-permeable substance, such as a resin or glass whose refractive index is lower than that of quartz type substances, filled in the voids adjacent to the connecting end. An optical fiber connecting section where an optical fiber having a plurality of voids in a clad around the periphery of a core is connected to another optical fiber, wherein the optical fiber is connected end-to-end to aforesaid another optical fiber through a refractive index matching agent whose refractive index at the minimum temperature in actual use is lower than that of the core.Type: ApplicationFiled: March 5, 2008Publication date: October 16, 2008Applicants: HITACHI CABLE, LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Yoshinori Kurosawa, Bing Yao, Kazumasa Ohsono, Masao Tachikura, Hisanori Nakai, Toshio Kurashima, Eiji Araki, Katumi Hiramatu
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Patent number: 7376315Abstract: An optical fiber which, at an optical fiber connecting end having a plurality of voids around the periphery of a core, has a light-permeable substance, such as a resin or glass whose refractive index is lower than that of quartz type substances, filled in the voids adjacent to the connecting end. An optical fiber connecting section where an optical fiber having a plurality of voids in a clad around the periphery of a core is connected to another optical fiber, wherein the optical fiber is connected end-to-end to aforesaid another optical fiber through a refractive index matching agent whose refractive index at the minimum temperature in actual use is lower than that of the core.Type: GrantFiled: June 30, 2004Date of Patent: May 20, 2008Assignees: Hitachi Cable, Ltd., Nippon Telegraph and Telephone Corp.Inventors: Yoshinori Kurosawa, Bing Yao, Kazumasa Ohsono, Masao Tachikura, Hisanori Nakai, Toshio Kurashima, Eiji Araki, Katumi Hiramatu
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Patent number: 7349610Abstract: An optical fiber coiled cord having a coil construction in which an optical fiber cord is spirally bent to obtain lengthwise stretchability, wherein the fiber coiled cord is provided with a stretch length control member which restricts lengthwise elongation.Type: GrantFiled: June 30, 2004Date of Patent: March 25, 2008Assignees: Hitachi Cable, Ltd., Nippon Telegraph and Telephone CorporationInventors: Kazumasa Ohsono, Masao Tachikura, Yoshinori Kurosawa, Yoshikazu Namekawa, Kenji Kawase, Toshio Kurashima, Eiji Araki, Katumi Hiramatu
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Publication number: 20060257086Abstract: An optical fiber coiled cord having a coil construction in which an optical fiber cord is spirally bent to obtain lengthwise stretchability, wherein the fiber coiled cord is provided with a stretch length control member which restricts lengthwise elongation.Type: ApplicationFiled: June 30, 2004Publication date: November 16, 2006Applicants: HITACHI CABLE, LTD., NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kazumasa Ohsono, Masao Tachikura, Yoshinori Kurosawa, Yoshikazu Namekawa, Kenji Kawase, Toshio Kurashima, Eiji Araki, Katumi Hiramatu
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Publication number: 20060204195Abstract: An optical fiber which, at an optical fiber connecting end having a plurality of voids around the periphery of a core, has a light-permeable substance, such as a resin or glass whose refractive index is lower than that of quartz type substances, filled in the voids adjacent to the connecting end. An optical fiber connecting section where an optical fiber having a plurality of voids in a clad around the periphery of a core is connected to another optical fiber, wherein the optical fiber is connected end-to-end to aforesaid another optical fiber through a refractive index matching agent whose refractive index at the minimum temperature in actual use is lower than that of the core.Type: ApplicationFiled: June 30, 2004Publication date: September 14, 2006Inventors: Yoshinori Kurosawa, Bing Yao, Kazumasa Ohsono, Masao Tachikura, Hisanori Nakai, Toshio Kurashima, Eiji Araki, Katumi Hiramatu
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Patent number: 6366348Abstract: The present invention provides an optical fiber distortion measuring apparatus and optical fiber distortion measuring method which make it possible to measure the amount of distortion of an optical fiber efficiently and in a short period of time. The time change waveform when a light pulse having a frequency of &ngr;1 is applied is compared with initial data (the time change waveform obtained in a case in which there is no distortion). Then, the light intensity L1 at a position Dx at which the light intensities do not agree is obtained. Next, the time change waveform is measured when a light pulse having a frequency of &ngr;2 is applied, and the light intensity L2 at position Dx is obtained. After this, the loss (resulting from distortion) in light intensities L1 and L2 is corrected, and light intensities LC1 and LC2 are obtained.Type: GrantFiled: April 18, 2000Date of Patent: April 2, 2002Assignees: Ando Electric Co., Ltd., Nippon Telegraph and Telephone CorporationInventors: Yasushi Sato, Haruyoshi Uchiyama, Toshio Kurashima
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Patent number: 6335788Abstract: The present invention relates to an optical-fiber characteristics measuring apparatus that does not require frequency conversion of pulse light which enters an optical fiber to be measured, and does not restrict the cycle period of the pulse light, thereby ensuring fast measuring of the characteristics of the optical fiber. This apparatus comprises an optical directional coupler, an optical pulse generator, a balanced-light reception circuit, a signal generation section and a mixer. The optical directional coupler branches coherent light into first and second coherent lights. The optical pulse generator converts the first coherent light into pulse light which in turn enters an optical fiber to be measured. Returned light whose frequency is shifted from that of the first coherent light by a predetermined frequency through reflection and scattering in the optical fiber to be measured enters the balanced-light reception circuit.Type: GrantFiled: April 11, 2000Date of Patent: January 1, 2002Assignees: Ando Electric Co., Ltd., Nippon Telegraph and Telephone CorporationInventors: Haruyoshi Uchiyama, Toshio Kurashima