# US 2017/0285258 A1 · Optical Fiber, and Optical-Fiber Production Method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0285258 A1 - Document ID: US20170285258A1 - Status: Published application - Kind: A1 - Application number: 15/513,911 - Filed: 2015-09-24 - Published: 2017-10-05 - Earliest claimed: 2014-09-24 - Assignees: Furukawa Electric Co., Ltd. - Applicants: Furukawa Electric Co., Ltd. - Inventors: Kunio Kokura - Web page: https://patentgrep.com/patent/US20170285258A1 ## CPC - G02B 6/02042: {Multicore optical fibres} - G02B 6/02395: {Glass optical fibre with a protective coating, e.g. two layer polymer coating deposited directly on a silica cladding surface during fibre manufacture (G02B6/02052, G02B6/02057, G02B6/024, G02B6/032, G02B6/105, G02B6/14 take precedence; coating on fibre gratings G02B6/02104; multilayer core or cladding G02B6/036; reinforcing splice joints G02B6/2558; optical cables, i.e. comprising protective structures external to the protective coating such as a jacket or plural coated optical fibres G02B6/44; coating of glass to obtain optical fibres C03C25/104)} - G02B 6/024: with polarisation maintaining properties - G02B 6/4404: {Multi-podded} - G02B 6/448: {Ribbon cables} - G02B 6/4482: {Code or colour marking} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract In this multi-core fiber, a plurality of cores are arranged at a prescribed interval, and the peripheries thereof are covered by a cladding having a lower refractive index than the plurality of cores. A resin coating is formed on the outer periphery of the cladding. A colored section is formed on a section of the outer surface of the resin coating in the peripheral direction. The colored section is formed continuously along the length direction of the multi-core fiber. In a multi-core fiber cross section orthogonal to the length direction, the position of a specific core and the peripheral position where the colored section is formed are substantially constant along the length direction of the multi-core fiber. In other words, in the multi-core fiber cross section orthogonal to the length direction, the position of the specific core and the position where the colored section is formed are substantially constant along the length direction of the multi-core fiber. ## Claims ### Claim 1 An optical fiber comprising: a core; a cladding that is formed on a periphery of the core and has a refractive index lower than that of the core; a resin coating that is formed on a periphery of the cladding: and a colored portion that is provided on a part of an outer surface of the resin coating in a circumferential direction thereof, wherein a form of a cross section of the optical fiber taken in a perpendicular direction to a longitudinal direction thereof has an orientation in a rotational direction with the longitudinal direction of the optical fiber as an axis; the colored portion is provided in such a manner that a positional relation between a position of the colored portion and a position of the core is substantially uniform over the longitudinal direction on a cross section of the optical fiber taken in a perpendicular direction to the longitudinal direction thereof. ### Claim 2 (depends on 1) The optical fiber according to claim 1, wherein: the colored portion is formed continuously or intermittently over an entire length of the optical fiber in the longitudinal direction thereof. ### Claim 3 (depends on 1) The optical fiber according to claim 1, wherein: the optical fiber is a multi-core fiber including a plurality of cores, and the colored portion is provided in such a manner that a positional relation between a position of the colored portion and a position of a particular core, which is one of the plurality of the cores, is substantially uniform over the longitudinal direction on a cross section of the multi-core fiber taken in a perpendicular direction to the longitudinal direction thereof. ### Claim 4 (depends on 3) The optical fiber according to claim 3, wherein: the particular core is an outermost core that is disposed at a position closest to the outer surface of the cladding on a cross section of the multi-core fiber taken in a perpendicular direction to the longitudinal direction thereof; and the colored portion is formed at a position closest to the particular core. ### Claim 5 (depends on 3) The optical fiber according to claim 3, wherein: the plurality of cores are disposed so as to have symmetry on a cross section of the multi-core fiber taken in a perpendicular direction to the longitudinal direction thereof; and the colored portion is formed at a position that is shifted from any of the symmetric axes. ### Claim 6 (depends on 3) The optical fiber according to claim 3, wherein: the colored portion is formed on at least two locations on a cross section of the multi-core fiber taken in a perpendicular direction to the longitudinal direction thereof. ### Claim 7 A method of producing an optical fiber, the optical fiber comprising: a core; a cladding that is formed on a periphery of the core and has a refractive index lower than that of the core; a resin coating that is formed on a periphery of the cladding; and a colored portion that is provided on a part of an outer surface of the resin coating in a circumferential direction thereof, the method including: a light introducing step which introduces light into a core of the fiber; a light leaking step which leaks the light introduced into the core to the outside of the optical fiber; a light detecting step which detects the light leaked in the light leaking step; an optical-fiber rotating step which rotates the optical fiber in a circumferential direction thereof so as to maintain the leaked light detected in the light detecting step to be substantially constant; and a resin applying step which applies a colored resin on a part of an outer surface of the resin coating in a circumferential direction thereof so that a positional relation between a position of the colored resin and a position of the core is substantially uniform over the longitudinal direction on a cross section perpendicular to the longitudinal direction of the optical fiber. ### Claim 8 (depends on 7) The method of producing an optical fiber according to claim 7, wherein the optical fiber is a multi-core fiber including a plurality of cores; and the colored portion is applied to a part of the outer surface of the resin coating in the circumferential direction in the resin applying step so that a positional relation between a position of the colored portion and a position of a particular core, which is one of the plurality of the cores, is substantially uniform over the longitudinal direction on a cross section of the multi-core fiber perpendicular to the longitudinal direction. ### Claim 9 (depends on 7) The method of producing an optical fiber according to claim 7, wherein the light is introduced from a bent portion of the bent optical fiber in the light introducing step. ### Claim 10 (depends on 7) The method of producing an optical fiber according to claim 7, wherein: the light is introduced from an end of the optical fiber in the light introducing step. ### Claim 11 (depends on 7) The method of producing an optical fiber according to claim 7, wherein: the optical-fiber rotating step rotates the optical fiber in its circumferential direction by tilting a rotational surface of a bobbin that winds up the optical fiber or a bobbin that reels out the optical fiber. ### Claim 12 (depends on 7) The method of producing an optical fiber according to claim 7, wherein: the optical-fiber rotating step rotates the optical fiber in its circumferential direction by tilting a rotational surface of a roller which is disposed either in front or rear of a detector that detects leak of the light in the light detecting step.