US 2010/0303429 A1Published application

Microstructured Optical Fiber Draw Method with In-Situ Vacuum Assisted Preform Consolidation

AssigneeThe Government of the United States of America, as represented by the Secretary of the Navy

InventorsDaniel J. Gibson, Jasbinder S. Sanghera, Frederic H. Kung, Ishwar D. Aggarwal

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Abstract

A method and apparatus for making a substantially void-free microstructured optical fiber using a one-step process is provided. A preform for the optical fiber is prepared, comprising an outer jacket made of solid glass, a cladding having a plurality of microtubes and/or microcanes arranged in a desired pattern within the jacket, and a core which may be solid or hollow, with the cladding and the core extending above the top of the outer jacket. The thus-prepared preform is placed into a fiber draw tower. As the fiber is drawn, negative gas pressure is applied to draw the canes together and consolidate the interfacial voids between the canes while positive gas pressure is applied to the preform to keep the holes of the microcanes open during the fiber drawing. The apparatus includes a jig having support tubes that are connected to a vacuum pump for application of the negative gas pressure and a vent tube connected to a gas supply for application of the positive gas pressure. The interfaces between the support tube and the outer jacket and between the vent tube and the cladding are sealed to ensure that the appropriate application of negative or positive pressure during the draw step is obtained. The preforms according to the present invention can include one or more components fabricated from specialty non-silica glass.

Claims29

Dependent claims

A method for manufacturing a microstructured optical fiber, comprising:

assembling a preform comprising a solid outer jacket, an inner core, and an intermediate cladding between the jacket and the core, the cladding including a plurality of glass microcanes arranged in a desired periodic pattern, the plurality of microcanes including at least one microtube having at least one longitudinal opening extending through the entire length thereof, the cladding and the core extending beyond an upper surface of the jacket, the preform including at least one interfacial void comprising a gap in the preform, the gap being one of a gap between adjacent microcanes and a gap between a microcane and the cladding;
placing the assembled preform into a jig connected to a draw tower, the jig including an outer tube connected to a source of negative gas pressure and an inner tube connected to a source of positive gas pressure;
securing the outer tube of the jig to an outer surface of the jacket so that the entirety of the preform is within the outer tube;
securing the inner tube of the jig to an outer surface of the cladding so that the cladding and the core of the preform is within inner tube;
applying negative gas pressure to the preform via the outer tube to remove air from the at least one interfacial void and prevent the formation of interstitial voids in the microstructured optical fiber;
applying positive gas pressure to the cladding and the core via the inner tube to prevent collapse of the at least one longitudinal opening, the negative and positive gas pressure being applied to sequentially consolidate the preform as it is being drawn into the optical fiber;
and
drawing the consolidated preform into the microstructured optical fiber, wherein the drawn fiber retains the at least one longitudinal opening and is substantially free from interstitial voids.

5 more elements

An apparatus for consolidating a preform for a microstructured optical fiber, the preform comprising an outer jacket, an inner core, and an intermediate cladding between the jacket and the core, the cladding comprising a plurality of microcanes arranged in a desired periodic pattern, at least one of the microcanes comprising a microtube having at least one longitudinal opening extending through the entire length thereof, the cladding and the core extending beyond an upper surface of the jacket, the preform including at least one interfacial void, the apparatus being operatively connected to a draw tower for drawing the preform into an optical fiber, the apparatus comprising:

an outer tube connected to a source of negative gas pressure and configured to sealingly fit around an outer surface of an exterior jacket of the preform;
an inner tube connected to a source of positive gas pressure and configured to sealingly fit around an outer surface of a cladding of the preform, the cladding extending above an upper surface of the jacket so that the cladding can be sealed within both the inner and the outer tube;
wherein negative gas pressure is applied to the preform via the outer tube to remove air from at least one interfacial void and prevent the formation of interstitial voids in the microstructured optical fiber;
wherein positive gas pressure is applied to the cladding and the core via the inner tube to prevent collapse of at least one longitudinal opening, the negative and positive gas pressure being applied to sequentially consolidate the preform as it is being drawn into the optical fiber.

1 more element

Dependencies are inferred from the claim text.