An optical fiber manufacturing method includes: a drawing step of heating one end portion of an optical fiber preform to melt and deform the one end portion and drawing an optical fiber, wherein in the drawing step, drawing is performed while applying pressure to a melted-deformed portion that is melted and deformed.

The application provides a method for automatically processing a conical tip of an optical fiber preform, including: step 10: suspending an optical fiber preform requiring conical tip processing on a suspension component, where the optical fiber preform moves downward vertically along with the suspension component; step 20: arranging a furnace body below the suspension component, where a preset depth is set inside the furnace body, and after the optical fiber preform moves to the preset depth inside the furnace body, the furnace body is heated; step 30: arranging an automatic cutting component below the furnace body, where a preset temperature is set inside the furnace body, after a temperature inside the furnace body reaches the preset temperature, a bottom of the furnace body is opened to make the optical fiber preform melt to form a conical tip, and the automatic cutting component cuts the molten conical tip.

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.

A wire-drawing optical fiber base material manufacturing method of heating an optical fiber base material by a heater and forming a drawing shape portion at an end portion. The manufacturing method includes: forming, by a flow-regulating member disposed adjacent to the heater, a gas flow such that formation, along a surface of the optical fiber base material, of a flow of a gas containing a Si compound generated from the optical fiber base material heated by the heater is inhibited; and forming, while maintaining the gas flow, the drawing shape portion by pulling part of the optical fiber base material softened by being heated by the heater.

A wire-drawing optical fiber base material manufacturing method of heating an optical fiber base material by a heater and forming a drawing shape portion at an end portion. The manufacturing method includes: forming, by a flow-regulating member disposed adjacent to the heater, a gas flow such that formation, along a surface of the optical fiber base material, of a flow of a gas containing a Si compound generated from the optical fiber base material heated by the heater is inhibited; and forming, while maintaining the gas flow, the drawing shape portion by pulling part of the optical fiber base material softened by being heated by the heater.

Provided is an elongating method for elongating a glass base material by heating the same while moving the same downward within an elongating apparatus, the glass base material including a transparent tapered section, wherein the transparent tapered section is located at an upper end of the glass base material and has an end face to which a suspension dummy formed from a glass pole is welded, the elongating method comprising steps for: starting to elongate the glass base material by heating the same, starting from a lower-end side thereof, by causing the glass base material to pass through a range within the elongating apparatus in which a preset elongating process temperature or higher is maintained; and after the tapered section enters the range, ending the elongating of the glass base material before the end face enters the range.

There is provided a method for producing a multicore optical fiber while depressurizing holes in a common cladding tube. A production method for a multicore optical fiber includes a preform forming step of forming a common cladding tube having a plurality of holes extending between a first end and a second end, an end-face working step of digging the common cladding tube from the second end to a predetermined depth to forming a third end, a connection step of connecting a glass tube to the second end, an insertion step of inserting core rods into the holes to the third end, a sealing step of sealing the first end, and a drawing step of spinning the multicore optical fiber while depressurizing the holes through the glass tube and combining the common cladding tube and the core rods from the first end.

There is provided a method for producing a multicore optical fiber while reducing the mass of a glass block to be connected to a common cladding tube. A production method for a multicore optical fiber includes in order, a preform forming step of forming a common cladding tube having a plurality of holes extending between a first end and a second end, an insertion step of inserting core rods in the holes in a state in which end portions of the core rods are recessed from the first end, a heat shrinkage step of reducing a diameter of the first end by heating, a sealing step of sealing the holes by connecting a glass block to the first end, and a drawing step of depressurizing insides of the holes from the second end and performing spinning from the first end while combining the common cladding tube and the core rods.

Provided is an elongating method for elongating a glass base material by heating the same while moving the same downward within an elongating apparatus, the glass base material including a transparent tapered section, wherein the transparent tapered section is located at an upper end of the glass base material and has an end face to which a suspension dummy formed from a glass pole is welded, the elongating method comprising steps for: starting to elongate the glass base material by heating the same, starting from a lower-end side thereof, by causing the glass base material to pass through a range within the elongating apparatus in which a preset elongating process temperature or higher is maintained; and after the tapered section enters the range, ending the elongating of the glass base material before the end face enters the range.

A wire-drawing optical fiber base material manufacturing method of heating an optical fiber base material by a heater and forming a drawing shape portion at an end portion. The manufacturing method includes: forming, by a flow-regulating member disposed adjacent to the heater, a gas flow such that formation, along a surface of the optical fiber base material, of a flow of a gas containing a Si compound generated from the optical fiber base material heated by the heater is inhibited; and forming, while maintaining the gas flow, the drawing shape portion by pulling part of the optical fiber base material softened by being heated by the heater.