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.

A seal structure for an optical fiber drawing furnace is for plugging a gap between an upper end opening of the fiber furnace, and an optical fiber glass preform wherein a seed rod and a taper portion are present in an upper portion thereof. The seal structure comprises a first cap member engaging the seed rod of the glass preform; a second cap member covering the taper portion of the glass preform and the first cap member; a spacer member disposed between the first and second cap member, supporting the second cap member, adjusting, via a positional adjustment structure, the height position of the second cap member in the axial direction, and causing the lower extremity of the second cap member to be at a position close to the taper portion; and a seal member which seals between the upper end opening and the glass preform and/or second cap member.

In some implementations, a substrate tube in a modified chemical vapor deposition process may rotate while glass precursors flow into the substrate tube at a fixed rate. Dopants may be delivered into the substrate tube while heat is applied to the substrate tube to deposit, on an inner wall of the substrate tube, a layer of material including the glass precursors and the dopants. A lateral position of an exit of an injection tube used to deliver the dopants may be adjusted while the substrate tube is rotated and heat is applied to the substrate tube such that the material deposited on the inner wall of the substrate tube has an azimuthally non-uniform doping concentration. Alternatively, a rotation of the substrate tube may be adjusted to create opposing temperature gradients within the substrate tube, causing non-uniform layer deposition to occur on different sides of the substrate tube in alternating passes.

The fabrication of sleeveless canes utilizes a preform with an array of glass canes in the preform. At least one tube-sleeve encircles the array of glass canes and is secured to the array of glass canes. The array of glass canes is moved into a furnace wherein the array of glass canes is heated. The furnace is maintained at a furnace temperature within the range of 2000 C. to 1700 C. and the array of glass canes is drawn from the furnace. The drawing of the array of glass canes both scales down the glass canes and elongates the glass canes. Maintaining the furnace at a furnace temperature within the range of 2000 C. to 1700 C. assures that the array of glass canes and the glass canes maintain their original shape.

An optical fiber drawing method where a glass base material passes through an opening provided in a drawing furnace from the material side and drawing is performed by suspending and descending the material into the drawing furnace while being sealed by a sealing mechanism provided in the vicinity of the opening, in which a first portion of the sealing mechanism seals a gap between an outer peripheral surface of the material and an inner surface of the opening when drawing starts and a tapered portion of the material starts passing through the first portion, and a second portion is disposed above the first portion before sealing by the first portion becomes ineffective, and then conduction between inside and outside of the drawing furnace is carried out to prevent fluctuation of pressure inside the furnace immediately after disposing the second portion and the conduction is interrupted when the material further descends.

In some implementations, a substrate tube in a modified chemical vapor deposition process may rotate while glass precursors flow into the substrate tube at a fixed rate. Dopants may be delivered into the substrate tube while heat is applied to the substrate tube to deposit, on an inner wall of the substrate tube, a layer of material including the glass precursors and the dopants. A lateral position of an exit of an injection tube used to deliver the dopants may be adjusted while the substrate tube is rotated and heat is applied to the substrate tube such that the material deposited on the inner wall of the substrate tube has an azimuthally non-uniform doping concentration. Alternatively, a rotation of the substrate tube may be adjusted to create opposing temperature gradients within the substrate tube, causing non-uniform layer deposition to occur on different sides of the substrate tube in alternating passes.

A preform material including a starter tip to facilitate an initial fiber draw from the preform within a furnace, wherein the tip comprises a vacuum-sealed tip to receive a plastic grip which attached to an end of a preform.

A sensor system to provide data for use to control manufacture of an optical fiber in microgravity including a diameter sensor to monitor a diameter of a fiber drawn from a preform material, a tension sensor to monitor tension of the fiber as the fiber is pulled from the preform material to a storage device and a controller in communication with at least one of the diameter sensor and the tension sensor to evaluate sensor data to determine at least one of a speed and rate at which the fiber is pulled from the preform material.

A system for controlling an ambient microgravity environment of a system for drawing optical fiber including a filter arranged to cleanse an environment from contaminants, a molecular sieve arranged in a series of at least one of meshes and baffles to dehumidify the environment, at least one of a pump and a fan to draw an environmental gas through the filter, through the molecular sieve and back in to an ambient environment and a housing in which the filter, molecular sieve and at least one of pump and fan reside.

A system for receiving optical fiber in microgravity including a spool portion to hold optical fiber created in microgravity, a catching mechanism to secure the fiber end to the spool and a capturing device that is extendable from near and retractable to near the spool portion to pull the optical fiber to the spool portion.