Heraeus Quartz North America LLC

Heraeus Quarzglas Gmbh & Co Kg

Heraeus Tenevo Gmbh

Kai Huei Chang

Qiulin Ma

Evan P Green

James E Beavers, Jr

Georges Levon Fattal

Oliver Ganz

Carl W Ponader

Jan Vydra

Manuel Rosenberger

Carl Ponader

Jong-Won Lee

James E Beavers Jr

To achieve a high degree of precision and an exact positioning of anti-resonant elements in a sufficiently stable and reproducible manner in an anti-resonant hollow-core fiber which has a hollow core extending along a fiber longitudinal axis and an inner jacket region that surrounds the hollow core, formation of anti-resonant element precursors includes formation of elongated pressure chambers, each of which adjoins a wall deformable under pressure and heat in the region of target positions of the anti-resonant elements. A section of the deformable wall is caused to protrude in the direction of a cladding tube inner bore, thereby forming an anti-resonant element or a precursor for same, while carrying out a process of elongating a primary preform to form the hollow-core fiber or further processing the primary preform to a secondary preform from which the hollow-core fiber is drawn.

Methods for producing a hollow-core fiber and for producing a preform for a hollow-core fiber

Method of producing glass components and preforms for use in the method. The preform includes a primary rod having a constant outside diameter and a flat bottom portion, wherein the primary rod comprises a core rod surrounded by at least one outer cladding layer; and a cylindrical sacrificial tip having a first end attached to the flat bottom portion of the primary rod, a second end opposite the first end, and a hollow interior region extending fully from the first end to the second end, wherein the sacrificial tip is circular in cross section and the first end of the sacrificial tip has a constant inside diameter and outside diameter along its entire length from the first end to the second end, and wherein the constant outside diameter is equal to the outside diameter of the primary rod. When the preform is heated in a furnace, the sacrificial tip melts and collapses into a drawing bulb which either draws the primary rod directly into the glass fiber or results in a tapered (i.e. tipped) preform for subsequent fiber draw. Material waste as well as the drip time is reduced and the cladding-to-core ratio, crucial for waveguide properties, is maintained for the whole preform compared to a square cut preform without the sacrificial tip.

Elongation method and preform for producing an optical glass component

An apparatus for producing large glass preforms with minimal clad to-core waveguide distortion from a glass body having a weight, an outer surface, core rods, and a cladding surrounding and separated from the core rods by a gap. The apparatus includes collars affixed to the top and bottom of the cladding; a spacer upon which the core rods rest; a first unit holding and supporting both the bottom collar and the spacer; a second unit holding and supporting the top collar; and a frame defining a heating zone having a heating element to heat the glass body. The weight of the glass body above and below the molten glass in the heating zone is supported by the first and second units without contacting the outer surface of the glass body.

Upward collapse process and apparatus for making glass preforms

An automated large outside diameter preform tipping process. A zone of the preform is heated inside a furnace and softened. The preform tip is shaped and the process is controlled by the movement of the glass above and below the heating zone and by sensing the weight of the lower part of the preform, which in effect is a measure of the viscosity of the softened material. Once the correct viscosity is reached, the bottom holder is moved away from the top holder with a non-linear, accelerated velocity profile (derived from the FEM simulation of glass flow) which is precisely programmed and controlled so that the preform tip is optimally shaped (usually short and sharp tipped) with minimum waste and waveguide distortion when drawn into a fiber. The same concept of the non-linear, accelerated velocity profile can also be applied to other tipping processes such as horizontal preform tipping processes.

Automated large outside diameter preform tipping process and resulting glass preforms

Method of producing glass components and preforms for use in the method. The preform includes a primary rod having a constant outside diameter and a square bottom and a sacrificial tip having a first end attached to the bottom of the primary rod, a second end opposite the first end, and a hollow interior region extending from the first end to the second end. The sacrificial tip is circular in cross section and the first end of the sacrificial tip has an outside diameter equal to the outside diameter of the primary rod. When the preform is heated in a furnace, the sacrificial tip melts and collapses into a drawing bulb which either draws the primary rod directly into the glass fiber or results in a tapered (i.e. tipped) preform for subsequent fiber draw. Material waste as well as the drip time is reduced and the cladding-to-core ratio, crucial for waveguide properties, is maintained for the whole preform compared to a square cut preform without the sacrificial tip.

Methods for preform and tube draw based on controlling forming zone viscosity determined by calculating a holding force exerted by the glass component in the forming zone on the strand being drawn below. The holding force may be calculated by determining a gravitational force applied to the strand and a pulling force applied to the strand by a pulling device, where the holding force is equal to the opposite of the algebraic sum of the gravitational and pulling forces. The holding force may also be calculated by measuring a stress-induced birefringence in the strand at a point between the forming zone and the pulling device, determining an amount of force applied to the strand at the point corresponding to the birefringence, and calculating the holding force by correcting the amount of force for a gravitational effect of the weight of the strand between the forming zone and the point.

Method for preform or tube drawing based on its viscosity

An apparatus and related process for producing large glass preforms with minimal clad to-core waveguide distortion from a glass body having a weight, an outer surface, core rods, and a cladding surrounding and separated from the core rods by a gap. The apparatus includes collars affixed to the top and bottom of the cladding; a spacer upon which the core rods rest; a first unit holding and supporting both the bottom collar and the spacer; a second unit holding and supporting the top collar; and a frame defining a heating zone having a heating element to heat the glass body. The weight of the glass body above and below the molten glass in the heating zone is supported by the first and second units without contacting the outer surface of the glass body.

Apparatus and method for producing elongated glass components with low bow. The apparatus may include a heating element to heat a bulk glass component where a strand may be drawn from the bulk glass component in a downward direction and a gripper device including a clamping element to support the strand while pulling or drawing it from the bulk glass component in a linear motion, and a low-friction mounting element attached to the clamping element which allows translational movement of the clamping element in an x-y plane. The gripper device may further be used to reduce bow in the strand while it is being drawn by moving the clamping element on the mounting element in a direction opposite the direction of any measured transverse acceleration.

Formation of elongated glass components with low bow using a gripper device

A method of forming a glass preform of predetermined length comprises providing a length of glass material to be separated to form a preform length and a remaining length; forming a notch in the glass material; inducing a tensile stress in excess of the tensile strength of the glass in an area adjacent to the notch; and separating the preform length from the remaining length at the notch.

Method for forming a glass preform

A method of manufacturing an optical fiber preform or an optical fiber is provided. The method includes the steps of: (a) providing a glass tube and a glass core rod; (b) inserting the glass core rod into the glass tube to form an assembled body; (c) heating the assembled body to cause the glass tube to collapse on and adhere to the glass core rod; and (d) treating an interface gap between the glass core rod and the glass tube during heating of at least a portion of the assembled body. Treating of the interface gap involves: (i) establishing a vacuum pressure in the interface gap, (ii) increasing a pressure of the interface gap by a treatment gas through the interface gap for a predetermined time, and (iii) re-establishing a vacuum pressure in the interface gap after the predetermined time has elapsed.

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Decatur, GA, United States of America

Kai Huei Chang