US-12623950-B2 - Light-based optical fiber heaters using hollow light pipes

Abstract

A method of processing an optical fiber that includes drawing an optical fiber along a fiber pathway through a hollow light pipe, wherein the hollow light pipe comprises a first end having an opening with a radius R p , a second end and a pipe body comprising a chamber extending from the first to the second end, the fiber pathway extending through the pipe body, and a reflective coating is disposed on the pipe body, and directing a light from a directed light source into the hollow light pipe through the opening such that the light is reflected by the reflective coating while propagating in the hollow light pipe, the optical fiber absorbing the light reflected by the reflective coating, wherein the light enters the opening of the hollow light pipe at an input angle in a range of from 10° to 70° with respect to the fiber pathway.

Inventors

• Anthony Sebastian Bauco
• Joel Patrick Carberry
• Ming-Jun Li
• Craig Daniel Nie
• Vincent Matteo Tagliamonti
• Chunfeng Zhou

Assignees

• CORNING INCORPORATED

Dates

Publication Date

20260512

Application Date

20221019

Claims (18)

1. 1 . A method of processing an optical fiber, the method comprising: drawing an optical fiber along a fiber pathway through a hollow light pipe, wherein: the hollow light pipe comprises a first end having an opening with a radius R p , a second end and a pipe body comprising a chamber extending from the first end to the second end, the fiber pathway extending through the pipe; and a reflective coating is disposed on the pipe body; and directing a light from a directed light source into the hollow light pipe through the opening of the first end such that the light is reflected by the reflective coating while propagating in the hollow light pipe, the optical fiber absorbing the light reflected by the reflective coating, wherein the light enters the opening of the first end of the hollow light pipe at an input angle in a range of from 10° to 70° with respect to the fiber pathway with a 1/e 2 diameter that is less than or equal to the radius R p of the opening of the first end, and wherein the light is polarized and enters the opening of the first end of the hollow light pipe such that Fresnel reflection losses are minimized.
2. 2 . The method of claim 1 , wherein a temperature of a core of the optical fiber at the opening of the first end is less than a glass transition temperature of the core of the optical fiber.
3. 3 . The method of claim 2 , wherein when the optical fiber absorbs the light, the temperature of the core of the optical fiber increases to greater than the glass transition temperature.
4. 4 . The method of claim 1 , wherein the fiber pathway is laterally offset from a central axis of the pipe body by a distance in a range of from 20% to 80% of the radius R p .
5. 5 . The method of claim 1 , wherein the directed light source is optically coupled to a steering mirror positioned to direct the light into the opening of the first end of the hollow light pipe at the input angle.
6. 6 . The method of claim 1 , wherein the input angle is in a range of from 30° to 70° with respect to the fiber pathway.
7. 7 . The method of claim 1 , wherein the reflective coating is disposed on an inner surface of the pipe body.
8. 8 . The method of claim 1 , wherein the reflective coating is disposed on an outside surface of the pipe body.
9. 9 . The method of claim 1 , wherein the reflective coating has a reflectivity of 95% or greater of the light.
10. 10 . The method of claim 1 , wherein a number of reflections of the light by the reflective coating is two or more while the light propagates in the hollow light pipe, the optical fiber absorbing the light after each of the reflections.
11. 11 . A method of processing an optical fiber, the method comprising: drawing an optical fiber along a fiber pathway through a hollow light pipe, wherein: the hollow light pipe comprises a first end having an opening with a radius R p , a second end and a pipe body comprising a chamber extending from the first end to the second end, the fiber pathway extending through the opening of the first end, wherein the fiber pathway is laterally offset from a central axis of the pipe body by a distance in a range of from 20% to 80% a radius R p of the opening of the first end; and a reflective coating is disposed on the pipe body, the reflective coating comprising a reflectivity of 95% or greater of a light; and directing the light from a directed light source into the hollow light pipe through the opening of the first end such that the light is reflected by the reflective coating while propagating in the hollow light pipe, the optical fiber absorbing the light reflected by the reflective coating, wherein the light enters the opening of the first end of the hollow light pipe at an input angle in a range of from 10° to 70° with respect to the fiber pathway with a 1/e 2 diameter that is less than or equal to the radius R p of the opening of the first end, and wherein the light is polarized and enters the opening of the first end of the hollow light pipe such that Fresnel reflection losses are minimized.
12. 12 . The method of claim 11 , wherein the hollow light pipe comprises a length of 200 mm or greater.
13. 13 . A system for processing an optical fiber, the system comprising: an optical draw tower comprising a fiber pathway, wherein the optical draw tower is configured to draw an optical fiber along the fiber pathway; a first hollow light pipe and a second hollow light pipe positioned along the optical draw tower, each hollow light pipe comprising a first end having an opening with a radius R p , a second end, and a pipe body comprising a chamber extending from the first end to the second end, wherein a reflective coating is disposed on the pipe body of each hollow light pipe and the fiber pathway extends through each hollow light pipe from the first end to the second end; a first directed light source optically coupled to the first end of the first hollow light pipe, wherein light output by the first directed light source comprises first polarized light, the first polarized light entering the opening of the first end of the first hollow light pipe such that Fresnel reflection losses are minimized; and a second directed light source optically coupled to the first end of the second hollow light pipe, wherein light output by the second directed light source comprises second polarized light, the second polarized light entering the opening of the first end of the second hollow light pipe such that Fresnel reflection losses are minimized.
14. 14 . The system of claim 13 , further comprising: a first optical system configured to direct light output by the first directed light source into the first hollow light pipe through the opening of the first end at an input angle in a range of from 10° to 70° with respect to the fiber pathway; and a second optical system configured to direct light output by the second directed light source into the second hollow light pipe through the opening of the first end at an input angle in a range of from 10° to 70° with respect to the fiber pathway.
15. 15 . The system of claim 14 , wherein the first optical system and the second optical system each comprise a first steering mirror and a second steering mirror.
16. 16 . The system of claim 13 , further comprising one or more end mirrors each comprising a fiber opening, wherein each of the one or more end mirrors is positioned in the first end or the second end of the first hollow light pipe or the second hollow light pipe, wherein the fiber pathway extends through the fiber opening of each end mirror.
17. 17 . The system of claim 13 , wherein the fiber pathway is laterally offset from a central axis of the pipe body of each of the first hollow light pipe and the second hollow light pipe by a distance in a range of from 20% to 80% the radius R p of the opening of the first end of each of the first hollow light pipe and the second hollow light pipe.
18. 18 . The system of claim 13 , wherein the reflective coating disposed on the pipe body of each hollow light pipe has a reflectivity of 95% or greater of the light.

Description

This application claims the benefit of priority under 35 U.S.C. § 120 of U.S. Provisional Application Ser. No. 63/270,250 filed on Oct. 21, 2021, the content of which is relied upon and incorporated herein by reference in its entirety. BACKGROUND Field The present specification generally relates to systems and methods of controlled heating of optical fibers. Technical Background Currently, optical fiber draw speeds to produce extremely low-loss fiber are limited due to increased attenuation penalties and the constraints of temperature in the heating and cooling processes. Slow cooling devices are used to improve the glass structural relaxation and reduce the fictive temperature. By reducing the fictive temperature, the dominant form of fiber attenuation, Rayleigh scattering, is reduced through slow cooling. Longer time in a slow cooling device can lower the fictive temperature further and therefore lower the fiber attenuation. However, as draw speeds increase, the fiber spends less time in the slow cooling device. The penalty is that the fictive temperature is not reduced as strongly and the fiber attenuation is increased. Accordingly, a need exists for an improved systems and methods for controlled heating of optical fibers during a draw process. SUMMARY According to a first aspect of the present disclosure, a method of processing an optical fiber includes drawing an optical fiber along a fiber pathway through a hollow light pipe, wherein the hollow light pipe comprises a first end having an opening with a radius Rp, a second end and a pipe body comprising a chamber extending from the first end to the second end, the fiber pathway extending through the pipe body, and a reflective coating is disposed on the pipe body. The method also includes directing a light from a directed light source into the hollow light pipe through the opening of the first end such that the light is reflected by the reflective coating while propagating in the hollow light pipe, the optical fiber absorbing the light reflected by the reflective coating, wherein the light enters the opening of the first end of the hollow light pipe at an input angle in a range of from 10° to 70° with respect to the fiber pathway. A second aspect of the present disclosure includes the method of the first aspect, wherein the light comprises a 1/e2 diameter that is less than or equal to the radius Rp. A third aspect of the present disclosure includes the method of the first aspect or the second aspect, wherein the fiber pathway is laterally offset from a central axis of the pipe body by a distance in a range of from 20% to 80% of the radius Rp. A fourth aspect of the present disclosure includes the method of any of the first through third aspects, wherein the directed light source is optically coupled to a steering mirror positioned to direct the light into the opening of the first end of the hollow light pipe at the input angle. A fifth aspect of the present disclosure includes the method of any of the first through fourth aspects, wherein the hollow light pipe comprises a length of in a range of from 100 mm to 10 meters. A sixth aspect of the present disclosure includes the method of any of the first through fifth aspects, wherein the input angle is in a range of from 30° to 70° with respect to the fiber pathway. A seventh aspect of the present disclosure includes the method of any of the first through sixth aspects, wherein the reflective coating is disposed on an inner surface of the pipe body. An eighth aspect of the present disclosure includes the method of any of the first through sixth aspects, wherein the reflective coating is disposed on an outside surface of the pipe body. An ninth aspect of the present disclosure includes the method of any of the first through eighth aspects, wherein the reflective coating has a reflectivity of 95% or greater of the light. A tenth aspect of the present disclosure includes the method of any of the first through ninth aspects, wherein the reflective coating comprises one or more of Au, Ag, and AgI. An eleventh aspect of the present disclosure includes the method of any of the first through tenth aspects, wherein the directed light source comprises a CO laser or a CO2 laser. A twelfth aspect of the present disclosure includes the method of any of the first through eleventh aspects, wherein a number of reflections of the light by the reflective coating is two or more while the light propagates in the hollow light pipe, the optical fiber absorbing the light after each of the reflections. A thirteenth aspect of the present disclosure includes the method of any of the first through twelfth aspects, wherein a temperature of a core of the optical fiber at the opening of the first end is less than a glass transition temperature of the core of the optical fiber. A fourteenth aspect of the present disclosure includes the method of the thirteenth aspect, wherein when the optical fiber absorbs the light, the temperature of