# US 2017/0283301 A1 · Optical fiber preform and method of manufacturing optical fiber > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0283301 A1 - Document ID: US20170283301A1 - Status: Published application - Kind: A1 - Application number: 15/631,442 - Filed: 2017-06-23 - Published: 2017-10-05 - Earliest claimed: 2015-01-09 - Assignees: Furukawa Electric Co., Ltd. - Applicants: Furukawa Electric Co., Ltd. - Inventors: Mitsuhiro KAWASAKI - Web page: https://patentgrep.com/patent/US20170283301A1 ## CPC - C03B 37/012: Manufacture of preforms for drawing fibres or filaments - C03B 37/01251: {Reshaping the ends} - C03B 37/0253: {Controlling or regulating (for glass fibre manufacture in general C03B37/07)} - C03B 37/02772: {shaping the preform lower end or bulb, e.g. pre-gobbing, controlling draw bulb shape, or preform draw start-up procedures} - G02B 6/02: Optical fibres with cladding {with or without a coating} - C03B 2205/40: Monitoring or regulating the draw tension or draw rate - C03B 2205/44: Monotoring or regulating the preform feed rate - C03B 2205/45: Monotoring or regulating the preform neck-down region with respect to position or shape - C03B 2205/47: Shaping the preform draw bulb before or during drawing - C03B 2205/72: Controlling or measuring the draw furnace temperature - C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract An optical fiber preform includes: a columnar portion having an approximately constant radius of r; and a taper portion located adjacent to the columnar portion in a lengthwise direction and having a radius decreasing along the lengthwise direction. The taper portion includes: a first taper portion including a portion having a radius varying between 0.9r and 0.6r; and a second taper portion including a portion having a radius varying between 0.4r and 0.15r. A diameter of the first taper portion in the portion having the radius varying between 0.9r and 0.6r decreases so as to form a maximum angle θ1 between 40 degrees and 60 degrees with respect to the columnar portion, a diameter of the second taper portion in the portion having the radius varying between 0.4r and 0.15r decreases so as to form an average angle θ2 between 5 degrees and 30 degrees with respect to a central axis in the lengthwise direction, and a volume of the taper portion is smaller than or equal to 45% of a volume of a column having a same outer diameter as a maximum outer diameter of the taper portion and having a same length as the taper portion. ## Claims ### Claim 1 An optical fiber preform comprising: a columnar portion having an approximately constant radius of r; and a taper portion located adjacent to the columnar portion in a lengthwise direction and having a radius decreasing along the lengthwise direction, wherein the taper portion includes: a first taper portion including a portion having a radius varying between 0.9r and 0.6r; and a second taper portion including a portion having a radius varying between 0.4r and 0.15r, a diameter of the first taper portion in the portion having the radius varying between 0.9r and 0.6r decreases so as to form a maximum angle θ1 between 40 degrees and 60 degrees with respect to the columnar portion, a diameter of the second taper portion in the portion having the radius varying between 0.4r and 0.15r decreases so as to form an average angle θ2 between 5 degrees and 30 degrees with respect to a central axis in the lengthwise direction, and a volume of the taper portion is smaller than or equal to 45% of a volume of a column having a same outer diameter as a maximum outer diameter of the taper portion and having a same length as the taper portion. ### Claim 2 (depends on 1) The optical fiber preform according to claim 1, further comprising a falling portion located at a tip side of the taper portion and functioning as a weight of the glass optical fiber when drawing of the optical fiber preform is started. ### Claim 3 (depends on 1) The optical fiber preform according to claim 1, wherein the columnar portion and the first taper portion are connected by a region having an outer circumference forming a curved surface with a radius of 30 mm or more along the lengthwise direction. ### Claim 4 (depends on 1) The optical fiber preform according to claim 1, wherein the first taper portion and the second taper portion are connected by a connection portion having an outer circumference forming a curved surface with a radius of 40 mm or more along the lengthwise direction. ### Claim 5 (depends on 1) The optical fiber preform according to claim 1, wherein the radius of the columnar portion is 40 mm or more. ### Claim 6 (depends on 1) The optical fiber preform according to claim 1, wherein the taper portion is formed by grinding. ### Claim 7 A method of manufacturing an optical fiber, the method comprising: drawing a glass optical fiber by heating and melting a tip portion of a taper portion of an optical fiber preform; and forming a coating on an outer circumference of the drawn glass optical fiber, wherein the optical fiber preform including: a columnar portion having an approximately constant radius of r; and the taper portion located adjacent to the columnar portion in a lengthwise direction and having a radius decreasing along the lengthwise direction, the taper portion includes: a first taper portion including a portion having a radius varying between 0.9r and 0.6r; and a second taper portion including a portion having a radius varying between 0.4r and 0.15r, a diameter of the first taper portion in the portion having the radius varying between 0.9r and 0.6r decreases so as to form a maximum angle θ1 between 40 degrees and 60 degrees with respect to the columnar portion, a diameter of the second taper portion in the portion having the radius varying between 0.4r and 0.15r decreases so as to form an average angle θ2 between 5 degrees and 30 degrees with respect to a central axis in the lengthwise direction, and a volume of the taper portion is smaller than or equal to 45% of a volume of a column having a same outer diameter as a maximum outer diameter of the taper portion and having a same length as the taper portion. ### Claim 8 (depends on 7) The method of manufacturing an optical fiber according to claim 7, further comprising a falling portion located at a tip side of the taper portion and functioning as a weight of the glass optical fiber when drawing of the optical fiber preform is started. ### Claim 9 (depends on 7) The method of manufacturing an optical fiber according to claim 7, wherein the columnar portion and the first taper portion are connected by a region having an outer circumference forming a curved surface with a radius of 30 mm or more along the lengthwise direction. ### Claim 10 (depends on 7) The method of manufacturing an optical fiber according to claim 7, wherein the first taper portion and the second taper portion are connected by a connection portion having an outer circumference forming a curved surface with a radius of 40 mm or more along the lengthwise direction. ### Claim 11 (depends on 7) The method of manufacturing an optical fiber according to claim 7, wherein the radius of the columnar portion is 40 mm or more. ### Claim 12 (depends on 7) The method of manufacturing an optical fiber according to claim 7, wherein the taper portion is formed by grinding.