AUTO-CLADDED LARGE-CORE OPTICAL FIBERS

• US 20110141555A1
• Filed: 12/14/2010
• Published: 06/16/2011
• Est. Priority Date: 09/26/2007
• Status: Active Grant

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Fermann, Martin E., Dong, Liang
• Granted Patent: US 8,970,947 B2
• Time in Patent Office: Days
• US Class Current: 359/341.3
• CPC Class Codes: G02B 6/02009 Large effective area or mode field radius, e.g. to reduce nonlinear effects in single mode fibres
• CPC Class Codes: G02B 6/02042 Multicore optical fibres
• CPC Class Codes: G02B 6/02366 Single ring of structures, e.g. "air clad"
• 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 6/03611 Highest index adjacent to central axis region, e.g. annular core, coaxial ring, centreline depression affecting waveguiding
• CPC Class Codes: G02B 6/03644 arranged - + -
• CPC Class Codes: H01S 3/06729 Peculiar transverse fibre profile
• CPC Class Codes: H01S 3/06733 Fibre having more than one cladding
• CPC Class Codes: H01S 3/06737 Fibre having multiple non-coaxial cores, e.g. multiple active cores or separate cores for pump and gain
• CPC Class Codes: H01S 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/08059 Constructional details of the reflector, e.g. shape mirrors in general G02B5/08; mountings for mirrors G02B7/18
• CPC Class Codes: H01S 3/094011 with bidirectional pumping, i.e. with injection of the pump light from both two ends of the fibre
• CPC Class Codes: H01S 3/094042 of a fibre laser
• CPC Class Codes: H01S 3/1608 erbium
• CPC Class Codes: H01S 3/1618 ytterbium

Abstract

Embodiments of auto-cladded optical fibers are described. The fibers may have a refractive index profile having a small relative refractive index change. For example, the fiber may include an auto-cladded structure having, e.g., a trough or gradient in the refractive index profile. A beam of light propagating in the fiber may be guided, at least in part, with the auto-cladded structure. In some embodiments, the optical fiber may be all glass. In some embodiments, the optical fiber may include a large-core or an ultra large-core.

Claims

1. An all-glass fiber comprising:

a core and cladding material, said core and cladding material comprising an interface, said core and cladding material selected from substantially identical glasses,

said fiber configured to support low-loss propagation of at least the lowest-order core mode,

wherein said fiber comprises at least one of an index trough at the core-cladding interface and an index gradient within said core.

2. An all-glass fiber according to claim 1, said core and cladding material being doped with a rare-earth material.

3. An all-glass fiber according to claim 2, said fiber further configured as an optical amplifier, said amplifier comprising a near diffraction-limited pump source coupled into said fiber core.

4. An all-glass fiber according to claim 1, said fiber comprising an index trough at the core-cladding interface.

5. The all-glass fiber according to claim 4, wherein said index trough comprises an index differential less than about 10⁻

4.

6. The all-glass fiber according to claim 4, wherein said index trough has a width in a range from about 1 μ

m to about 50 μ

m.

7. The all-glass fiber according to claim 1, wherein a refractive index difference between said core material and said cladding material is less than about 10⁻

4.

8. An all glass fiber according to claim 1, said fiber core further comprising an index gradient inside said core with a maximum index differential of 1×

10<sup>−

4</sup> inside said core.

9. An all glass fiber according to claim 8, said index gradient arising from frozen-in stresses inside said core.

10. An all glass fiber according to claim 8, said index gradient arising from compositional variations inside said core.

11. An all glass fiber according to claim 1, said cladding material further including additional features disposed within said cladding, said features comprising a glass made of a different material than said cladding material.

12. An all glass fiber according to claim 11, said cladding material having a higher thermal expansion coefficient than the core material.

40. An all-glass fiber according to claim 1, said fiber comprising multiple cores.

13. An all-glass fiber comprising a core and cladding material, said core and cladding material further having a common interface, said core and cladding material selected from glasses with an index differential less than about 10⁻

4, said fiber further comprising an index trough at the core-cladding interface.

14. An all-glass fiber according to claim 13, said glass fiber further comprising a rare-earth dopant inside said core.

15. An all-glass fiber according to claim 13, said fiber core further comprising an index gradient inside said core with a maximum index differential of 1×

10<sup>−

4</sup> inside said core.

16. An all-glass fiber according to claim 13, said index gradient arising from frozen-in stresses inside said core.

17. An all-glass fiber according to claim 13, said fiber core further comprising an index gradient inside said core resulting from a non-uniform heat distribution within said fiber core.

18. A fiber amplifier comprising the all-glass fiber according to claim 13, said fiber amplifier being cladding pumped.

19. An all-glass fiber amplifier comprising:

a rare-earth doped core and cladding material, said core and cladding material comprising an interface;

a near diffraction-limited pump source coupled into said rare-earth doped core;

said rare-earth doped core configured to amplify at least the lowest-order core mode,

wherein said fiber amplifier comprises at least one of an index trough at the core-cladding interface and an index gradient within said core.

20. An all-glass fiber amplifier according to claim 19,

wherein said rare-earth doping level in said core and cladding is substantially the same and said index trough is sufficiently large that said fiber amplifier guides and amplifies at least the lowest order core mode.

24. An all-glass fiber amplifier according to claim 19, said fiber core comprising an index gradient within said core with a maximum index differential of 1×

10<sup>−

4</sup> within said core, said core having a dimension at least about 20 μ

m, and wherein an index profile within said core exhibits a maximum at about the center of said core and decreases from the center to an edge of said core.

21. -23. (canceled)

25. -39. (canceled)

41. -42. (canceled)

43. A multi-core fiber amplifier comprising a fiber comprising multiple cores, the amplifier further comprising:

an optical pump source; and

an optical signal source,

said optical pump source configured to be delivered into at least some of said multiple cores via a diffractive beam splitter.

44. -49. (canceled)