Non-circular multicore fiber and method of manufacture

Patent metadata

Field	Value
Publication number	US-9841556-B2
Application number	US-201615137336-A
Country	US
Kind code	B2
Filing date	Apr 25, 2016
Priority date	May 29, 2015
Publication date	Dec 12, 2017
Grant date	Dec 12, 2017

Abstract

A multicore fiber is provided. The multicore fiber includes a plurality of cores spaced apart from one another, and a cladding surrounding the plurality of cores and defining a substantially rectangular or cross-sectional shape having four corners. Each corner has a radius of curvature of less than 1000 microns. The multicore fiber may be drawn from a preform in a circular draw furnace in which a ratio of a maximum cross-sectional dimension of the preform to an inside diameter of the preform to an inside diameter of the draw furnace is greater than 0.60. The multicore fiber may have maxima reference surface.

First claim

What is claimed is:

1. A method of forming a multicore fiber comprising the steps of:
forming a preform having a plurality of cores and cladding surrounding the cores, wherein the preform has a non-circular cross section with a plurality of corners and a maximum dimension across the cross section of the preform;
inserting the preform in a draw furnace having a substantially circular cross section such that a ratio of the maximum dimension of the preform to an inside diameter of the draw furnace is greater than 0.60; and
drawing a multicore fiber from the preform to achieve a reduction in cross-sectional size as the fiber is drawn while substantially maintaining a non-circular cross-sectional shape and the plurality of corners of the preform, wherein the multicore fiber is drawn at a draw speed of V draw from a preform having maximum cross section dimension D p in a draw furnace having peak temperature in Kelvin of T peak and hot zone length of L draw under conditions that result in non-dimensional draw parameter X=(L draw ×σ)/(V draw ×μ×D p ) to be less than 5×10 −6 ; wherein σ is the glass surface tension defined as σ (dynes/cm)=233.28+0.035×T peak and μ is the glass viscosity defined as μ (Poise)=Exp[−13.738+(60604.7/T peak )].

2. The method of claim 1 , wherein the multicore fiber is drawn under conditions having non-dimensional draw parameter X less than 2×10 −6 .

3. The method of claim 1 , wherein the multicore fiber is drawn under conditions having non-dimensional draw parameter X less than 1×10 −6 .

4. The method of claim 1 , wherein the ratio of the maximum dimension of the preform to the inside diameter of the draw furnace is greater than 0.80.

5. The method of claim 1 , wherein the ratio of the maximum dimension of the preform to the inside diameter of the draw furnace is greater than 0.90.

6. The method of claim 1 , wherein the ratio of the maximum dimension of the preform to the inside diameter of the draw furnace is greater than 0.95.

7. The method of claim 1 , wherein the fiber has a substantially rectangular cross-sectional shape having four corners, wherein each corner of the fiber has a radius of curvature of less than 1000 microns.

8. The method of claim 7 , wherein each corner of the fiber has a radius of curvature of less than 500 microns.

9. The method of claim 7 , wherein each corner of the fiber has a radius of curvature of less than 250 microns.

10. A method of forming a multicore fiber comprising the steps of:
forming a preform having a plurality of cores and cladding surrounding the cores, wherein the preform has a non-circular cross section with a plurality of corners and a maximum dimension across the cross section of the preform;
inserting the preform in a draw furnace having a substantially circular cross section such that a ratio of the maximum dimension of the preform to an inside diameter of the draw furnace is greater than 0.70; and
drawing a multicore fiber from the preform to achieve a reduction in cross-sectional size as the fiber is drawn while substantially maintaining a non-circular cross-sectional shape and the plurality of corners of the preform.

11. A method of forming a multicore fiber comprising the steps of:
forming a preform having a plurality of cores and cladding surrounding the cores, wherein the preform has a non-circular cross section with a plurality of corners and a maximum dimension across the cross section of the preform;
inserting the preform in a draw furnace having a substantially circular cross section such that a ratio of the maximum dimension of the preform to an inside diameter of the draw furnace is greater than 0.60; and
drawing a multicore fiber from the preform to achieve a reduction in cross-sectional size as the fiber is drawn while substantially maintaining a non-circular cross-sectional shape and the plurality of corners of the preform, wherein the step of forming the non-circular preform comprises:
forming a plurality of core canes each having a core surrounded by cladding;
processing each core cane to include at least one flat lateral surface;
aligning the flat lateral surface of adjoining canes; and
consolidating the aligned canes to form the preform.

12. The method of claim 11 , wherein the step of processing each core cane comprises machining each core cane to include at least one flat lateral surface.

13. The method of claim 11 , wherein the step of processing each core cane to include at least one flat lateral surface comprises processing each core cane to include four flat lateral surfaces.

14. A method of forming a multicore fiber comprising the steps of:
forming a preform having a plurality of cores and cladding surrounding the cores, wherein the preform has a non-circular cross section with a plurality of corners and a maximum dimension across the cross section of the preform;
inserting the preform in a draw furnace having a substantially circular cross section such that a ratio of the maximum dimension of the preform to an inside diameter of the draw furnace is greater than 0.60; and
drawing a multicore fiber from the preform to achieve a reduction in cross-sectional size as the fiber is drawn while substantially maintaining a non-circular cross-sectional shape and the plurality of corners of the preform, wherein the fiber comprises an enlarged maxima member near each of the corners, and further comprises reduced maxima between adjacent corners so that the enlarged maxima members serve as alignment points.

Assignees

• Corning Inc

Inventors

• Butler Douglas Llewellyn
• Hawtof Daniel Warren
• Layton Iii Rick Charles
• Meda Gautam
• Stone Iii John
• Tandon Pushkar

Classifications

• G02B6/02042 Primary

  Multicore optical fibres · CPC title

• C03B2203/12

  Non-circular or non-elliptical cross-section, e.g. planar core · CPC title

• G02B6/00

  Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings · CPC title

• C03B37/029

  Furnaces therefor · CPC title

• C03B37/01205

  starting from tubes, rods, fibres or filaments (C03B37/014 takes precedence) · CPC title