SINGLE MODE PROPAGATION IN FIBERS AND RODS WITH LARGE LEAKAGE CHANNELS

• US 20140044139A1
• Filed: 10/15/2013
• Published: 02/13/2014
• Est. Priority Date: 05/20/2005
• Status: Active Grant

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Dong, Liang, Fermann, Martin E., Wong, William
• Granted Patent: US 8,873,916 B2
• Time in Patent Office: Days
• US Class Current: 372/6
• CPC Class Codes: G02B 6/00 Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
• CPC Class Codes: G02B 6/02 Optical fibres with cladding with or without a coating
• 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 6/02033 Core or cladding made from organic material, e.g. polymeric material G02B1/04 takes precedence
• CPC Class Codes: G02B 6/02357 Property of longitudinal structures or background material varies radially and/or azimuthally in the cladding, e.g. size, spacing, periodicity, shape, refractive index, graded index, quasiperiodic, quasicrystals
• CPC Class Codes: G02B 6/02361 Longitudinal structures forming multiple layers around the core, e.g. arranged in multiple rings with each ring having longitudinal elements at substantially the same radial distance from the core, having rotational symmetry about the fibre axis
• CPC Class Codes: G02B 6/02366 Single ring of structures, e.g. "air clad"
• CPC Class Codes: G02B 6/02371 Cross section of longitudinal structures is non-circular
• CPC Class Codes: G02B 6/024 with polarisation maintaining properties
• CPC Class Codes: G02B 6/036 core or cladding comprising multiple layers multicore optical fibres G02B6/02042; microstructured properties G02B6/02295; omniguide fibres G02B6/023
• CPC Class Codes: G02B 6/03633 arranged - -
• CPC Class Codes: G02B 6/03694 Multiple layers differing in properties other than the refractive index, e.g. attenuation, diffusion, stress properties
• CPC Class Codes: G02B 6/24 Coupling light guides
• CPC Class Codes: G02B 6/26 Optical coupling means G02B6/36, G02B6/42 take precedence
• CPC Class Codes: G02B 6/262 Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements
• CPC Class Codes: G02B 6/32 having lens focusing means positioned between opposed fibre ends with lens being an integral part of the single fibre end G02B6/262
• CPC Class Codes: G02F 1/0134 in optical waveguides
• CPC Class Codes: H01S 2302/00 Amplification / lasing wavelength
• CPC Class Codes: H01S 3/0057 Temporal shaping, e.g. pulse compression, frequency chirping soliton generation and propagation G02F1/3513, H01S3/063 and H01S3/108
• CPC Class Codes: H01S 3/02 Constructional details housings or packages of fibre lasers H01S3/06704
• CPC Class Codes: H01S 3/06708 : Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering optical fibres as passive waveguides G02B6/02
• CPC Class Codes: H01S 3/06729 : Peculiar transverse fibre profile
• CPC Class Codes: H01S 3/06745 : Tapering of the fibre, core or active region
• CPC Class Codes: H01S 3/06754 : Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/094007 : Cladding pumping, i.e. pump light propagating in a clad surrounding the active core
• CPC Class Codes: H01S 3/1618 : ytterbium
• CPC Class Codes: H01S 3/2308 : Amplifier arrangements, e.g. MOPA
• CPC Class Codes: H01S 3/302 : in an optical fibre

Abstract

Various embodiments include large cores fibers that can propagate few modes or a single mode while introducing loss to higher order modes. Some of these fibers are holey fibers that comprising cladding features such as air-holes. Additional embodiments described herein include holey rods. The rods and fibers may be used in many optical systems including optical amplification systems, lasers, short pulse generators, Q-switched lasers, etc. and may be used for example for micromachining.

Claims

1. A polarization-maintaining (PM) optical fiber for propagating at least one lower order mode having a wavelength, λ

, while limiting propagation of higher order modes having a wavelength, λ

, by providing said higher order modes with a higher loss than said at least one lower order mode at said wavelength, λ

, said optical fiber comprising;

a first cladding region comprising one or more cladding features; and

a core region surrounded by said first cladding region, said core region having a width of at least about 20 micrometers, said one or more cladding features configured to substantially confine propagation of said at least one lower order mode to said core region,

wherein said one or more cladding features are arranged in no more than two layers around core region, and

wherein said core region, said first cladding region, or both said core region and said first cladding region have a two dimensional asymmetry that provides birefringence

2. The PM optical fiber of claim 1, wherein said width of said core region is less than about 300 micrometers.

3. The PM optical fiber of claim 1, wherein said one or more cladding features are arranged in no more than one layer around said core region.

4. The PM optical fiber of claim 1, wherein said PM optical fiber comprises at least one stress-producing region.

5. The PM optical fiber of claim 1, wherein said one or more cladding features comprises stress elements.

6. The PM optical fiber of claim 1, wherein said one or more cladding features comprise ellipses.

7. The PM optical fiber of claim 1, wherein said core region is elliptical or rectangular.

8. The PM optical fiber of claim 1, wherein said one or more cladding features comprise features having different sizes.

9. The PM optical fiber of claim 1, wherein said one or more cladding features comprise features having an asymmetrical distribution.

10. The PM optical fiber of claim 1, wherein said core region comprises stress elements.

11. The PM optical fiber of claim 1, wherein at least a portion of said PM optical fiber is coiled.

12. The PM optical fiber of claim 1, comprising a birefringent crystalline material.

13. The PM optical fiber of claim 1, wherein said one or more cladding features comprise two or more cladding features having a maximum feature size, d, and an average center-to-center spacing, Λ

, and wherein d/Λ

is greater than about 0.4 and less than about 0.9.

14. The PM optical fiber of claim 1, wherein said one or more cladding features have a maximum feature size, d, that yields a ratio of d/λ

that is in a range from about 5 to 100.

15. The PM optical fiber of claim 1, wherein said one or more cladding features comprise two or more cladding features disposed in a matrix material and separated by bridges having a maximum bridge width, a, said bridge comprising matrix material, wherein a/λ

is in a range from about 5 to 100

16. The PM optical fiber of claim 1, wherein said PM optical fiber is configured to provide a loss for said higher order modes of at least about 0.5 dB.

17. The PM optical fiber of claim 1, wherein said one or more cladding features are disposed in a matrix material, and at least one of said one or more cladding features comprises material having a refractive index less than a refractive index of said matrix material.

18. The PM optical fiber of claim 1, further comprising a second cladding region surrounding said first cladding region.

19. The PM optical fiber of claim 1, further comprising a pump guide surrounding said first cladding region and a pump cladding surrounding said pump guide.

20. The PM optical fiber of claim 19, further comprising an outer layer surrounding said pump cladding.

21. The PM optical fiber of claim 1, wherein said core region is doped with one or more dopants to provide optical gain.

22. The PM optical fiber of claim 21, wherein at least one dopant comprises a rare earth ion.

23. A laser system comprising:

an optical cavity formed by reflective elements, said optical cavity comprising;

the PM optical fiber of claim 1;

a gain medium doped with at least one dopant; and

an optical pump source configured to provide pump light to said gain medium.

24. The laser system of claim 23, wherein said PM optical fiber comprises said gain medium.

25. The laser system of claim 23, wherein at least one of said reflective elements comprises an optical fiber Bragg grating.

26. The laser system of claim 23, further comprising a fast optical switch included in said optical cavity.

27. An optical amplification system comprising:

the PM optical fiber of claim 1;

a gain medium; and

an optical pump source optically coupled to said gain medium and configured to provide pump light to the gain medium.

28. The optical amplification system of claim 27, wherein said PM optical fiber comprises said gain medium.

29. The optical amplification system of claim 27, wherein the PM optical fiber comprises a pump guide disposed around said core region and said one or more cladding features, said pump guide arranged to receive said pump light from said optical pump source.

30. The optical amplification system of claim 27, further comprising a frequency conversion element.

31. A chirped pulse amplification system comprising:

the optical amplification system of claim 27; and

a pulse compressor.