Bend resistant multimode optical fiber

• US 20080166094A1
• Filed: 12/20/2007
• Published: 07/10/2008
• Est. Priority Date: 01/08/2007
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Li, Ming-Jun, Bookbinder, Dana Craig, Nolan, Daniel Aloysius
• Granted Patent: US 7,787,731 B2
• Time in Patent Office: Days
• US Class Current: 385/124
• CPC Class Codes: C03B 2203/14 Non-solid, i.e. hollow products, e.g. hollow clad or with core-clad interface
• CPC Class Codes: C03B 2203/23 Double or multiple optical cladding profiles
• CPC Class Codes: C03B 2203/26 Parabolic or graded index [GRIN] core profile
• CPC Class Codes: C03B 2203/28 Large core fibres, e.g. with a core diameter greater than 60 micrometers
• CPC Class Codes: G02B 6/02333 Core having higher refractive index than cladding, e.g. solid core, effective index guiding
• CPC Class Codes: G02B 6/02342 characterised by cladding features, i.e. light confining region
• CPC Class Codes: G02B 6/0288 Multimode fibre, e.g. graded index core for compensating modal dispersion
• CPC Class Codes: G02B 6/032 with non solid core or cladding G02B6/02295 takes precedence
• CPC Class Codes: G02B 6/03627 arranged - +
• CPC Class Codes: G02B 6/03633 arranged - -
• CPC Class Codes: G02B 6/0365 arranged - - +
• CPC Class Codes: G02B 6/14 Mode converters

Abstract

Bend resistant multimode optical fibers are disclosed herein. Multimode optical fibers disclosed herein comprise a core region and a cladding region surrounding and directly adjacent to the core region, the cladding region comprising a depressed-index annular portion comprising a depressed relative refractive index.

Claims

1. A multimode optical fiber comprising:

a graded index glass core; and

a cladding surrounding and in contact with the core, the cladding comprising a depressed-index annular portion surrounding the core, wherein the depressed-index annular portion comprises glass comprising a plurality of holes.

2. The multimode optical fiber of claim 1 wherein the depressed-index annular portion is in contact with the core.

3. The multimode optical fiber of claim 1 wherein the cladding further comprises an outer annular portion surrounding the depressed-index annular portion wherein the outer annular portion comprises hole-free glass.

4. The multimode optical fiber of claim 1 wherein the cladding further comprises an inner annular portion surrounding the core wherein the inner annular portion comprises hole-free glass.

5. The multimode optical fiber of claim 4 wherein the depressed-index annular portion surrounds the inner annular portion.

6. The multimode optical fiber of claim 5 wherein the cladding further comprises an outer hole-free annular portion surrounding the depressed-index annular portion.

7. The multimode optical fiber of claim 1 wherein the plurality of holes in the depressed-index annular portion comprises a maximum hole diameter of 15 microns.

8. The multimode optical fiber of claim 6 wherein the plurality of holes in the depressed-index annular portion comprises a hole diameter ranging from >

0.005 microns to <

1 micron.

9. The multimode optical fiber of claim 1 wherein the holes are non-periodically disposed in the depressed-index annular portion.

10. The multimode optical fiber of claim 1 wherein the depressed-index annular portion extends to an outermost periphery of the cladding.

11. The multimode optical fiber of claim 8 wherein the outer annular portion extends to an outermost periphery of the cladding.

12. A multimode optical fiber comprising:

a graded index glass core; and

a glass cladding surrounding and in contact with the core, the cladding comprising a depressed-index annular portion;

wherein the core has a maximum relative refractive index Δ

1MAX, in %, at 850 nm;

wherein the core and the cladding provide (a) a bandwidth of greater than 750 MHz-km at a wavelength of 850 nm, and (b) a 1 turn 10 mm diameter mandrel wrap attenuation increase at a wavelength of 1550 nm, in dB, of less than or equal to the product of two times (1/Δ

1MAX)².

13. The multimode optical fiber of claim 12 wherein the depressed-index annular portion comprises glass comprising a plurality of holes, or fluorine-doped glass, or fluorine-doped glass comprising a plurality of holes.

14. The multimode optical fiber of claim 13 wherein the depressed-index annular portion is offset from the core.

15. The multimode optical fiber of claim 13 wherein the depressed-index annular portion is in contact with the core.

16. The multimode optical fiber of claim 13 wherein the depressed-index annular portion extends to an outermost periphery of the cladding.

17. The multimode optical fiber of claim 13 wherein the cladding further comprises a hole-free glass outer annular portion which extends to an outermost periphery of the cladding.

18. The multimode optical fiber of claim 13 wherein the fiber is spun.

19. The multimode optical fiber of claim 13 wherein the restricted mode launch bandwidth is greater than 1 GHz-km at a wavelength of 850 nm.

20. A multimode optical fiber comprising:

a graded index glass core extending from a centerline to a radius R1, wherein R1>

20 microns; and

a cladding surrounding and in contact with the core, the cladding comprising a depressed-index annular portion and an outer annular portion, wherein the depressed-index annular portion surrounds the core, and the outer annular portion surrounds and is in contact with the depressed-index annular portion;

wherein the core has a maximum relative refractive index at 850 nm, Δ

1MAX, less than or equal to 0.80%;

wherein the depressed-index annular portion surrounds and is in contact with the core and has a minimum relative refractive index, Δ

2MIN; and

wherein Δ

1MAX>

0>

Δ

2MIN.

21. The multimode optical fiber of claim 20 wherein the depressed-index annular portion has a profile volume with an absolute magnitude of less than 200%-μ

m².

22. The multimode optical fiber of claim 20 wherein the depressed-index annular portion comprises glass comprising a plurality of holes, or fluorine-doped glass, or fluorine-doped glass comprising a plurality of holes.

23. A multimode optical fiber comprising:

a graded index glass core extending from a centerline to a radius R1; and

a cladding surrounding and in contact with the core, the cladding comprising an inner annular portion, and a depressed-index annular portion;

wherein;

the inner annular portion surrounds the core;

the depressed-index annular portion surrounds the inner annular portion;

the core has a maximum relative refractive index Δ

1MAX at 850 nm;

the inner annular portion has a maximum relative refractive index Δ

2MAX at 850 nm;

the depressed-index annular portion has a minimum relative refractive index Δ

3MIN at 850 nm;

Δ

1MAX>

Δ

2MAX>

Δ

3MIN; and

the inner annular portion has a width W2>

0.4 microns.