US-12623949-B2 - Optical fiber draw production systems, pressure devices and methods applying pressure to optical fiber

Abstract

Optical fiber draw production systems, pressure devices, and methods of fabrication of optical fiber are disclosed. In one embodiment, a method of forming an optical fiber includes heating a preform to draw the optical fiber through a draw furnace, and passing the optical fiber through a pressure device while the optical fiber is still forming, wherein a pressure within the pressure device is greater than an atmospheric pressure.

Inventors

• Nikolaos Pantelis Kladias
• Ming-Jun Li
• Bruce Warren Reding
• Pushkar Tandon
• Kevin Lee Wasson

Assignees

• CORNING INCORPORATED

Dates

Publication Date

20260512

Application Date

20221026

Claims (20)

1. 1 . A method of processing an optical fiber comprising: drawing the optical fiber from a preform through a draw furnace operable to draw the optical fiber from the preform; directing the optical fiber in a downstream direction along a process pathway, the optical fiber having a forming point at a first position along the process pathway, the optical fiber having a forming point temperature T fp at the forming point; and passing the optical fiber through a pressure device downstream from the draw furnace and operable to receive the optical fiber from the draw furnace and subject the optical fiber to an applied pressure greater than 10 atm at a second position along the process pathway, the second position upstream of the first position, and the optical fiber having a temperature T 1 at the second position, wherein T fp −150° C.≤T 1 ≤T fp +100° C.
2. 2 . The method of claim 1 , wherein T fp is between 1500° C. and 1700° C., including endpoints.
3. 3 . The method of claim 1 , further comprising directing the optical fiber to a cooling device positioned along the process pathway, the cooling device configured to cool the optical fiber at a rate less than 5000° C./s.
4. 4 . The method of claim 3 , wherein the optical fiber enters the cooling device at a temperature greater than T 1 −100° C.
5. 5 . The method of claim 3 , wherein a residence time of the optical fiber inside of the cooling device is less than 0.5 seconds.
6. 6 . A fiber draw production system comprising: a draw furnace operable to draw an optical fiber from a preform in a downstream direction along a process pathway, the optical fiber having a forming point at a first position along the process pathway, the optical fiber having a forming point temperature T fp at the forming point; and a pressure device downstream from the draw furnace and operable to receive the optical fiber from the draw furnace and subject the optical fiber to an applied pressure greater than 10 atm at a second position along the process pathway, the second position upstream of the first position, and the optical fiber having a temperature T 1 at the second position, wherein T fp −150° C.≤T 1 ≤T fp +100° C.
7. 7 . The fiber draw production system of claim 6 , wherein the fiber draw production system is such that a residence time of the optical fiber within the pressure device is greater than 40 msec.
8. 8 . The fiber draw production system of claim 6 , wherein the pressure device comprises a pressure chamber, an inlet nozzle at an entrance end of the pressure chamber, and an exit nozzle at an exit of the pressure chamber.
9. 9 . The fiber draw production system of claim 8 , wherein: the exit nozzle comprises a straight section and a tapered section; the straight section has a diameter that is less than 150 μm and a length within a range of 50 μm and 150 μm, including end points; the tapered section has an increasing diameter defined by a taper angle; and a flow rate to the exit nozzle is less than 100 g/min.
10. 10 . The fiber draw production system of claim 6 , wherein the pressure device comprises at least one nozzle.
11. 11 . The fiber draw production system of claim 10 , wherein the at least one nozzle comprises a series of step bearings, wherein each step bearing of the series of step bearings comprises a first segment having a first diameter and a first length and a second segment having a second diameter and a second length.
12. 12 . The fiber draw production system of claim 11 , wherein the first diameter is greater than the second diameter and the first length is shorter than the second length.
13. 13 . The fiber draw production system of claim 6 , further comprising a cooling device positioned along the process pathway, the cooling device configured to cool the optical fiber at a rate less than 5000° C./s.
14. 14 . The fiber draw production system of claim 13 , wherein the optical fiber enters the cooling device at a temperature greater than T1-100° C.
15. 15 . The fiber draw production system of claim 13 , wherein a residence time of the optical fiber inside of the cooling device is less than 0.5 seconds.
16. 16 . A pressure device for applying pressure to an optical fiber drawn from a draw furnace along a process pathway, the optical fiber having a forming point at a first position along the process pathway, the optical fiber having a forming point temperature Tip at the forming point, and the pressure device comprising: a pressure chamber comprising an entrance end and an exit end; an entrance nozzle at the entrance end; an exit nozzle at the exit end; and an inlet fluidly coupled to the entrance nozzle, wherein: the pressure device is operable to receive the optical fiber at a second position along the process pathway and subject the optical fiber to an applied pressure greater than 10 atm; the exit nozzle comprises a straight section and a tapered section; the straight section has a diameter that is less than 150 μm and a length within a range of 50 μm and 150 μm, including end points; the tapered section has an increasing diameter defined by a taper angle; and a flow rate to the exit nozzle is less than 100 g/min.
17. 17 . The pressure device of claim 16 , wherein the exit nozzle comprises a series of nozzles.
18. 18 . The pressure device of claim 16 , wherein: at least one of the entrance nozzle and the exit nozzle comprises a series of step bearings; and each step bearing of the series of step bearings comprises a first segment having a first diameter and a first length and a second segment having a second diameter and a second length.
19. 19 . The pressure device of claim 18 , wherein the first diameter is greater than the second diameter and the first length is shorter than the second length.
20. 20 . The pressure device of claim 16 , wherein the inlet has a taper angle of less than or equal to 5 degrees.

Description

FIELD This Application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 63/273,390, filed on Oct. 29, 2021, the content of which is relied upon and incorporated herein by reference in its entirety. BACKGROUND The present disclosure is directed to the production of optical fiber and, more particularly, to the production of optical fiber having reduced Rayleigh scattering. Optical fiber is increasingly being used for a variety of applications, including but not limited to broadband voice, video, and data transmission. As bandwidth demands increase optical fiber is migrating deeper into communication networks such as in fiber-to-the-premises applications such as FTTx, 5G, and the like. However, traditional optical fiber inherently induces optical loss in optical signals that propagate within the optical fiber. This optical loss produces signal degradation that can affect network performance. One source of optical loss is the presence of structural voids within the optical fiber that cause Rayleigh scattering and overall signal attenuation. Consequently, there exists an unresolved need for optical fiber draw production systems and methods of optical fiber production that reduce the presence of structural voids. SUMMARY The present disclosure is directed to optical fiber draw production systems, pressure devices, and methods of fabrication of optical fiber that apply pressure to the optical fiber immediately following the draw furnace and at or near the point of optical fiber formation to reduce the presence of structural voids in the formed optical fiber. In one embodiment, a method of processing an optical fiber includes drawing an optical fiber from a preform and directing the optical fiber in a downstream direction along a process pathway. The optical fiber has a forming point at a first position along the process pathway, the optical fiber having a forming point temperature Tfp at the forming point. The method further includes subjecting the optical fiber to an applied pressure greater than 10 atm at a second position along the process pathway. The second position is upstream of the first position, and the optical fiber has a temperature Ti at the second position, wherein Tfp−150° C.≤T1≤Tfp+100° C. In another embodiment, a fiber draw production system includes a draw furnace and a pressure device. The draw furnace is operable to draw an optical fiber from a preform in a downstream direction along a process pathway. The optical fiber has a forming point at a first position along the process pathway. The optical fiber having a forming point temperature Tfp at the forming point. As a non-limiting example, the optical fiber may have a forming point temperature Tfp between 1500° C. and 1700° C., including endpoints. The pressure device is downstream from the draw furnace and is operable to receive an optical fiber from the draw furnace and subject the optical fiber to an applied pressure greater than 10 atm at a second position along the process pathway. The second position is upstream of the first position, and the optical fiber having a temperature Ti at the second position, wherein Tfp−150° C.≤T1≤Tfp+100° C. In yet another embodiment, a pressure device for applying pressure to an optical fiber drawn from a draw furnace along a process pathway includes a pressure chamber having an entrance end and an exit end. The optical fiber has a forming point at a first position along the process pathway and a forming point temperature Tfp at the forming point. The pressure device also includes an entrance nozzle at the entrance end, an exit nozzle at the exit end, and a tapered inlet fluidly coupled to the entrance nozzle. The tapered inlet has a taper angle of less than or equal to 5 degrees. The pressure device is operable to receive the optical fiber at a second position along the process pathway. The second position is upstream of the first position, and the optical fiber has a temperature Ti at the second position, where Tfp−150° C.≤T1≤Tfp+100° C. Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the same as described herein, including the detailed description that follows, the claims, as well as the appended drawings. It is to be understood that both the foregoing general description and the following detailed description present embodiments that are intended to provide an overview or framework for understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments and together with the description serve to explain the principles and operation. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 schematically illustrates a perspective view of an opti