Multi-core optical fibers with single mode and multimode core elements

• US 9,151,887 B2
• Filed: 09/04/2013
• Issued: 10/06/2015
• Est. Priority Date: 09/04/2012
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Hoover, Brett Jason, Li, Ming-Jun
• Primary Examiner(s): BLEVINS, JERRY M
• Application Number:
  US14/017,362
• Publication Number:
  US 20140064687A1
• Time in Patent Office: 762 Days
• Field of Search: 385/126
• US Class Current: 1/1
• CPC Class Codes: G02B 6/02042 Multicore optical fibres
• CPC Class Codes: G02B 6/0281 Graded index region forming part of the central core segment, e.g. alpha profile, triangular, trapezoidal core G02B6/0288, G02B6/0286 take precedence
• CPC Class Codes: G02B 6/03644 arranged - + -
• CPC Class Codes: G02B 6/0365 arranged - - +

Abstract

Multi-core optical fibers are disclosed herein. According to one embodiment, a multi-core optical fiber includes a common outer cladding formed from silica-based glass and having a cladding index of refraction n_cl. At least one single mode core element may be disposed in the common outer cladding. The at least one single mode core element may have a maximum index of refraction n_{1 sm}. In addition, at least one multimode core element may be disposed in the common outer cladding, the at least one multimode core element having a maximum index of refraction n_{1 mm}. The maximum refractive index n_{1 sm} of the at least one single mode core element may be greater than the cladding index of refraction n_cl, the maximum refractive index n_{1 mm} of the at least one multi-mode core element may be greater than n_cl, and a center-to-center spacing between adjacent core elements is greater than or equal to 25 μm.

Claims

1. A multi-core optical fiber comprising:

a common outer cladding formed from silica-based glass and having a cladding index of refraction n_cl;

a plurality of single mode core elements formed from silica-based glass and disposed in the common outer cladding, the plurality of single mode core elements having a maximum index of refraction n_{1 sm}; and

a plurality of multimode core elements formed from silica-based glass and disposed in the common outer cladding, the plurality of multimode core elements having a maximum index of refraction n_{1 mm}, wherein;

n_{1 sm} is greater than n_cl;

n_{1 mm} is greater than n_cl;

individual ones of the plurality of single mode core elements comprise a low-index annulus formed from silica-based glass surrounding the core element, the low-index annulus having a radial width greater than or equal to 1 μ

m and less than or equal to 6 μ

m; and

a center-to-center spacing between adjacent core elements is greater than or equal to 25 μ

m.

2. The multi-core optical fiber of claim 1, wherein a relative refractive index Δ

_{1 mm} of individual ones of the plurality of multimode core elements relative to the common outer cladding is greater than or equal to 0.2%.

3. The multi-core optical fiber of claim 1, wherein a relative refractive index Δ

_{1 sm} of individual ones of the plurality of single mode core elements relative to the common outer cladding is greater than or equal to 0.2%.

4. The multi-core optical fiber of claim 1, wherein a relative refractive index Δ

₂ of the low-index annulus to the common outer cladding is less than or equal to −

0.1%.

5. The multi-core optical fiber of claim 1, wherein the low-index annulus is spaced apart from the core element by an offset spacing which is greater than or equal to 3 μ

m and less than or equal to 5 μ

m.

6. The multi-core optical fiber of claim 1, wherein a cross talk between adjacent core elements is less than −

30 dB.

7. A multi-core optical fiber comprising:

a common outer cladding formed from silica-based glass;

a plurality of single mode core elements formed from silica-based glass and disposed in the common outer cladding, individual ones of the plurality of single mode core elements having a relative refractive index Δ

_{1 sm} greater than or equal to 0.2% relative to the common outer cladding; and

a plurality of multimode core elements formed from silica-based glass and disposed in the common outer cladding, individual ones of the plurality of multimode core elements having a relative refractive index Δ

_{1 mm} greater than or equal to 0.2% relative to the common outer cladding, wherein a center-to-center spacing between adjacent core elements is greater than or equal to 25 μ

m, wherein individual ones of the plurality of single mode core elements, individual ones of the plurality of multimode core elements, or individual ones of both the plurality of single mode core elements and the plurality of multimode core elements comprise a low-index annulus formed from silica-based glass surrounding the core element, the low index annulus being spaced apart from the core element by an offset spacing which is less than or equal to 2 μ

m or greater than or equal to 3 μ

m and less than or equal to 5 μ

m.

8. The multi-core optical fiber of claim 7, wherein a relative refractive index Δ

₂ of the low-index annulus to the common outer cladding is less than the relative refractive index Δ

_{1 mm} and the relative refractive index Δ

_{1 sm}.

9. The multi-core optical fiber of claim 7, wherein individual ones of the plurality of single mode core elements have core radii greater than or equal to about 3 μ

m and less than or equal to about 10 μ

m.

10. The multi-core optical fiber of claim 7, wherein individual ones of the plurality of multimode core elements have core radii greater than or equal to about 5 μ

m and less than or equal to about 35 μ

m.

11. The multi-core optical fiber of claim 7, wherein the relative refractive index Δ

_{1 sm} is greater than or equal to about 0.2% and less than or equal to about 0.5%.

12. The multi-core optical fiber of claim 7, wherein the relative refractive index Δ

_{1 mm} is greater than or equal to 0.4% and less than or equal to 1.0%.

13. The multi-core optical fiber of claim 7, wherein the low-index annulus has a relative refractive index Δ

₂ of less than or equal to −

0.1% relative to the common outer cladding and a radial width greater than or equal to 1 μ

m and less than or equal to 6 μ

m.

14. The multi-core optical fiber of claim 7, wherein individual ones of the plurality of single mode core elements comprise the low-index annulus and the offset spacing is greater than or equal to 3 μ

m and less than or equal to 5 μ

m.

15. The multi-core optical fiber of claim 7, wherein individual ones of the plurality of multimode core elements comprise the low-index annulus and the offset spacing is less than or equal to 2 μ

m.

16. A multi-core optical fiber comprising:

a common outer cladding formed from silica-based glass and having a cladding index of refraction n_c1;

a plurality of single mode core elements formed from silica-based glass and disposed in the common outer cladding, the plurality of single mode core elements having a maximum index of refraction n_{1 sm}; and

a plurality of multimode core elements formed from silica-based glass and disposed in the common outer cladding, the plurality of multimode core elements having a maximum index of refraction n_{1 mm}, wherein;

n_{1 sm} is greater than n_cl;

n_{1 mm} is greater than n_cl;

individual ones of the plurality of multi-mode core elements comprise a low-index annulus formed from silica-based glass surrounding the core element, the low-index annulus having a radial width greater than or equal to 1 μ

m and less than or equal to 6 μ

m; and

a center-to-center spacing between adjacent core elements is greater than or equal to 25 μ

m.

17. The multi-core optical fiber of claim 16, wherein the low-index annulus is spaced apart from the core element by an offset spacing which is less than or equal to 2 μ

m.

18. The multi-core optical fiber of claim 16, wherein a relative refractive index Δ

₂ of the low-index annulus to the common outer cladding is less than or equal to −

0.1%.

19. The multi-core optical fiber of claim 16, wherein a relative refractive index Δ

_{1 mm} of individual ones of the plurality of multimode core elements relative to the common outer cladding is greater than or equal to 0.2%.

20. The multi-core optical fiber of claim 16, wherein a relative refractive index Δ

_{1 sm} of individual ones of the plurality of single mode core elements relative to the common outer cladding is greater than or equal to 0.2%.