US-12617709-B2 - In-tower optical fiber bending

Abstract

The invention discloses a draw tower ( 100 ) comprising a top end zone ( 108 ) to insert a preform along with fluid and the preform is melted into an optical fiber ( 106 ) that exits from a bottom end zone ( 110 ). The draw tower ( 100 ) includes a plurality of air knives ( 112 ) distorting optical fiber path such that partially uncooled optical fiber deviates from a vertical path to a bended path wherein the plurality of air knives ( 112 ) is a plurality of openings arranged such that to cause distortion on the vertical path of the optical fiber ( 106 ) in the draw tower ( 100 ) and the plurality of openings is a combination of one or more of a suction and pumping of the fluid. Further, the bended path length is greater than a vertical path length and is defined by laminar flow for at least 70% of the bended path length.

Inventors

• Badri Gomatam

Assignees

• STERLITE TECHNOLOGIES LIMITED

Dates

Publication Date

20260505

Application Date

20230301

Priority Date

20220331

Claims (6)

1. 1 . An optical fiber draw tower ( 100 ) configured to melt a preform ( 104 ) into an optical fiber ( 106 ), the optical fiber draw tower ( 100 ) comprising: a top end zone ( 108 ) and a bottom end zone ( 110 ), wherein the preform ( 104 ) is inserted at the top end zone ( 108 ) and is melted into the optical fiber ( 106 ) that exits from the bottom end zone ( 110 ), wherein a fluid is inserted into the optical fiber draw tower ( 100 ) from the top end zone ( 108 ); and a plurality of air knives ( 112 ) that distorts an optical fiber path such that partially uncooled optical fiber deviates from a vertical path and follows a bended path, wherein the vertical path is defined by an axis parallel to the optical fiber draw tower ( 100 ), wherein the plurality of air knives ( 112 ) is a plurality of openings arranged to cause distortion on the vertical path of the optical fiber ( 106 ) in the optical fiber draw tower ( 100 ), wherein the plurality of openings is a combination of one or more of a suction and pumping of the fluid, wherein a length of the bended path is greater than a length of the vertical path, wherein the length of the bended path is defined by laminar flow for at least 70% of the length of the bended path.
2. 2 . The optical fiber draw tower ( 100 ) as claimed in claim 1 , wherein the plurality of air knives ( 112 ) modifies mass flow of the fluid in a predefined manner to distort the optical fiber path inside the optical fiber draw tower ( 100 ).
3. 3 . The optical fiber draw tower ( 100 ) as claimed in claim 1 , wherein the plurality of air knives ( 112 ) is arranged such that the fluid enters or exits the optical fiber draw tower ( 100 ) at an angle of 0-89 degrees with respect to the vertical path.
4. 4 . The optical fiber draw tower ( 100 ) as claimed in claim 1 , wherein the bended path length is at least 10% greater than the vertical path length of the optical fiber ( 106 ).
5. 5 . The optical fiber draw tower ( 100 ) as claimed in claim 1 , wherein the plurality of air knives ( 112 ) comprises a first set of air knives and a second set of air knives, and wherein the optical fiber ( 106 ) is directed from the first set of air knives to the second set of air knives in an alternate manner and at predefined angles such that a bending angle of the first set of air knives is different than a bending angle of the second set of air knives that results in multiple partial turns ( 120 ) to the optical fiber ( 106 ).
6. 6 . The optical fiber draw tower ( 100 ) as claimed in claim 5 , wherein distorting the vertical path of the optical fiber ( 106 ) by the multiple partial turns comprises: applying external force to uncooled optical fiber ( 106 ) at one or more predefined zones ( 114 , 116 , 118 ) in the optical fiber draw tower ( 100 ); and altering a path of a fluid at the one or more predefined zones ( 114 , 116 , 118 ) in the optical fiber draw tower ( 100 ) due to application of the external force causing the uncooled optical fiber ( 106 ) to deviate from the vertical path into a bended path.

Description

COPYRIGHT STATEMENT A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. CROSS REFERENCE TO RELATED APPLICATION This application claims the benefit of Indian Application No. 202211019367 titled “IN-TOWER OPTICAL FIBER BENDING” filed by the applicant on Mar. 31, 2022, which is incorporated herein by reference in its entirety. FIELD The present invention relates to the field of optical fiber manufacturing equipment and more particularly, relates to an optical fiber draw tower facilitating in-tower optical fiber bending and an optical fiber processing method. BACKGROUND OF THE INVENTION With the progress of communication networks in recent years, optical fiber communication networks have been rapidly developed. Optical fibers are useful in a wide variety of applications, including the telecommunications industry for voice, video, and data transmissions. Currently, a demand for reducing the manufacturing cost of an optical fiber is ever increasing, in addition to an improvement of optical transmission characteristics of the optical fiber. In recent years, significant advancements have been made in the manufacture of optical waveguide fiber, which in turn have increased the usable light carrying capacity of the fiber. However, it is well known that electromagnetic radiation traveling through an optical waveguide fiber is subject to attenuation or lose due to several mechanisms. Although some of these mechanisms cannot be reduced, others have been eliminated, or at least substantially reduced. Manufacturing methods for producing optical fibers typically include drawing optical fiber from a glass perform that is heated in a draw furnace, cooling the drawn fiber, and coating the fiber after it has sufficiently cooled. However, the process parameters employed by the fiber manufacturing process may have a significant impact on the resultant performance characteristics of the drawn fiber. During optical fiber manufacturing, glass preforms are heated at a high temperature significantly above the softening point of the glass and drawn at a high draw down ratio and a high draw speed to produce an optical fiber due to which the glass preforms do not reach an equilibrium state. This results in the production of optical fiber with high fictive temperature, which is undesirable as it results in increased attenuation, i.e. signal loss. One way to address the aforesaid drawbacks is modifying fiber processing conditions that can allow manufacturing the optical fiber with lower fictive temperature. Efforts to reduce fictive temperature have emphasized slow cooling to stabilize the optical fiber in a state closer to an equilibrium state. Prolonged cooling of an optical fiber at temperatures in the glass transition range of the fiber is another strategy for reducing fictive temperature. US Patent Application No. US20190256400 titled “Low attenuation optical fiber” discloses an optical fiber with low attenuation. In particular, the optical fiber is produced under conditions that reduce fictive temperature. U.S. Pat. No. 10,696,580B2 titled “Optical fiber with low fictive temperature” discloses an optical fiber with low fictive temperature along with a system and method for making the optical fiber. WIPO Patent Application No. WO2014046274A1 titled “Optical fiber fabrication method” discloses a method in which the fictive temperature is sufficiently reduced to fabricate an optical fiber with low loss and high yield. U.S. Pat. No. 6,565,775B2 titled “Method of cooling an optical fiber while it is being drawn” discloses a method of cooling an optical fiber during drawing through contact with at least one cooling fluid in at least one cooling area. In particular, the temperature profile of each cooling area is established so that the fictive temperature of a cladding of the optical fiber is maximized, and the fictive temperature of a core of the optical fiber is minimized. However, there are a number of drawbacks in the current technologies for manufacturing optical fibers with lower fictive temperature. In particular, the fictive temperature is not reduced to a satisfactory/desired level by the currently used manufacturing methods due to a short residence time. Subsequently, the structure of the glass preforms does not reach a required equilibrium state as the decrease in the fictive temperature is small. Moreover, the existing manufacturing methods utilize a turn or fold mechanism and mechanically move the path of the draw outside the draw tower assembly. As a result, the optical fiber cannot be drawn within required fictive temperature and attenuation values without dimensionally changing the existing draw tower set-up. This,