LARGE CORE HOLEY FIBERS

• US 20080056656A1
• Filed: 09/06/2007
• Published: 03/06/2008
• Est. Priority Date: 01/16/2004
• Status: Active Grant

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Harter, Donald, Wong, William, Dong, Liang
• Granted Patent: US 8,285,099 B2
• Time in Patent Office: Days
• US Class Current: 385/125
• 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 6/02047 Dual mode fibre G02B6/105 takes precedence
• CPC Class Codes: G02B 6/02328 Hollow or gas filled core
• CPC Class Codes: G02B 6/02338 Structured core, e.g. core contains more than one material, non-constant refractive index distribution in core, asymmetric or non-circular elements in core unit, multiple cores, insertions between core and clad
• CPC Class Codes: G02B 6/02342 characterised by cladding features, i.e. light confining region
• 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 6/024 with polarisation maintaining properties
• CPC Class Codes: G02B 6/032 with non solid core or cladding G02B6/02295 takes precedence
• CPC Class Codes: G02B 6/14 Mode converters
• 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: H01S 3/06716 Fibre compositions per se C03C13/04or doping with active elements lasing materials in general H01S3/14
• 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 3/06741 Photonic crystal fibre, i.e. the fibre having a photonic bandgap
• CPC Class Codes: H01S 3/06754 Fibre amplifiers H01S3/06708 takes precedence

Abstract

Various types of holey fiber provide optical propagation. In various embodiments, for example, a large core holey fiber comprises a cladding region formed by large holes arranged in few layers. The number of layers or rows of holes about the large core can be used to coarse tune the leakage losses of the fundamental and higher modes of a signal, thereby allowing the non-fundamental modes to be substantially eliminated by leakage over a given length of fiber. Fine tuning of leakage losses can be performed by adjusting the hole dimension and/or the hole spacing to yield a desired operation with a desired leakage loss of the fundamental mode. Resulting holely fibers have a large hole dimension and spacing, and thus a large core, when compared to traditional fibers and conventional fibers that propagate a single mode. Other loss mechanisms, such as bend loss and modal spacing can be utilized for selected modes of operation of holey fibers. Other embodiments are also provided.

Claims

1. A hollow core photonic band gap fiber that provides optical amplification, said hollow core photonic band gap fiber comprising:

a cladding region comprising a plurality of cladding features disposed in a matrix;

a hollow core region surrounded by said cladding region, said hollow core having a hollow region formed therein, said plurality of cladding features arranged to form a photonic band gap to substantially confine propagation of light in said hollow core region; and

a gain region having optical gain that is disposed proximal to said hollow region such that said light propagating through said hollow core region is amplified by said gain provided by said gain region.

2. The hollow core photonic band gap fiber of claim 1, wherein said gain region is doped with a material that provides gain.

3. The hollow core photonic band gap fiber of claim 1, wherein said gain region comprises an annular region surrounding said hollow core.

4. An optical fiber amplifier comprising:

an optical gain fiber for propagating a single mode, said optical gain fiber providing optical gain, said optical gain fiber comprising;

(i) a cladding region comprising a plurality of cladding features disposed in a matrix, said plurality of cladding features having an average spacing, Λ

, and an average size, d; and

(ii) a core region surrounded by said cladding region, said plurality of cladding features substantially confining propagation of said single mode to said core region, said plurality of cladding features having (i) sufficient average spacing, Λ

, to provide an increased effective core size, 2ρ

, and (ii) a sufficient average size, d, to provide substantial confinement of light within said core region,

wherein the difference between said average size, d, and said average spacing, Λ

, is less than about 50% of said average spacing, Λ

.

5. An optical fiber amplifier comprising:

an optical pump source; and

an optical gain fiber optical fiber for propagating a single optical mode, said optical gain fiber providing optical gain, said optical gain fiber comprising;

(i) a cladding region comprising a plurality of cladding features disposed in a matrix, said plurality of cladding features having an average spacing, Λ

, and an average size, d; and

(ii) a core region surrounded by said cladding region, said plurality of cladding features substantially confining propagation of said single optical mode to said core region, said plurality of cladding features having (i) sufficient average spacing, Λ

, to provide an increased effective core size, 2ρ

, and (ii) a sufficient average size, d, to provide substantial confinement of light within said core region,

wherein said average size, d, is substantially equal to said average spacing, Λ

.

6. A CW fiber laser comprising:

a resonant cavity formed by at least partially reflective surfaces; and

an optical fiber in said resonant cavity, said optical fiber having optical gain, said optical fiber propagating a single optical mode, said optical fiber comprising;

(i) a cladding region comprising a plurality of cladding features disposed in a matrix, said plurality of cladding features having an average spacing, Λ

, and an average size, d; and

(ii) a core region surrounded by said cladding region, said plurality of cladding features substantially confining propagation of said single optical mode to said core region, said plurality of cladding features having (i) sufficient average spacing, Λ

, to provide an increased effective core size, 2ρ

, and (ii) a sufficient average size, d, to provide substantial confinement of light within said core region,

wherein said average size, d, and said average spacing, Λ

, have values at least about 20 micrometers to provide an effective core size of at least about 20 micrometers.