In-line, high energy fiber chirped pulse amplification system

• US 7,257,302 B2
• Filed: 06/30/2003
• Issued: 08/14/2007
• Est. Priority Date: 06/03/2003
• Status: Active Grant

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Harter, Donald J., Fermann, Martin E., Imeshev, Gennady, Hartl, Ingmar
• Primary Examiner(s): Hellner; Mark
• Application Number:
  US10/608,233
• Publication Number:
  US 20040263950A1
• Time in Patent Office: 1,506 Days
• Field of Search: 359/332, 359/333, 359/337.21, 359/569, 385/123, 385/125, 385/127
• US Class Current: 385/125
• CPC Class Codes: H01S 3/005 Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B
• 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 3/0085 Modulating the output, i.e. the laser beam is modulated outside the laser cavity
• CPC Class Codes: H01S 3/0092 Nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity nonlinear frequency conversion per se G02F1/35
• CPC Class Codes: H01S 3/06712 Polarising fibre; Polariser
• CPC Class Codes: H01S 3/06725 Fibre characterized by a specific dispersion, e.g. for pulse shaping in soliton lasers or for dispersion compensating [DCF]
• 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 3/10015 by monitoring or controlling, e.g. attenuating, the input signal

Abstract

By writing non-linear chirp into fiber Bragg gratings, greater control over dispersion compensation in CPA systems is obtained, such that, for example, the dispersion profile of the fiber Bragg grating and a bulk compressor may be matched. An iterative method of writing the fiber grating can reduce the group delay ripple to very low levels; and adaptive control of the fiber grating dispersion profile can further reduce these levels, while in addition offering greater acceptable yield in the manufacture of such gratings. Fiber Bragg gratings may be designed so as to provide customized pulse shapes optimized for various end uses, such as micromachining, for example, and may also be used to counteract gain-narrowing in a downstream amplifier.

Claims

1. A polarization maintaining air-clad fiber, comprising:

a core region;

a material cladding region surrounding said core;

an air-cladding substantially surrounding said first cladding region; and

a layer surrounding said air cladding,

where polarization maintaining operation of said fiber is obtained by the incorporation of stress producing regions that are fully disposed within and surrounded by said material cladding region.

2. A polarization maintaining air-clad fiber as claimed in claim 1, wherein said fiber comprises additional cladding regions.

14. The polarization maintaining air-clad fiber of claim 1, wherein the core region has a diameter >

15 μ

m.

15. The polarization maintaining air-clad fiber of claim 1, wherein the material cladding region has a cross-section having an outer surface having at least three-fold symmetry.

16. The polarization maintaining air-clad fiber of claim 1, wherein said air-cladding comprises a single ring of air-holes.

3. A polarization maintaining fiber, comprising:

a fiber core having a diameter >

15 μ

m;

a first cladding surrounding said core; and

further including stress-producing regions incorporated therein;

an air cladding substantially surrounding said first cladding; and

a third cladding surrounding said air cladding.

17. The polarization maintaining fiber of claim 3, wherein the first cladding fully surrounds the stress-producing regions.

18. The polarization maintaining fiber of claim 3, wherein the first cladding has a cross-section having an outer surface having at least three-fold symmetry.

19. The polarization maintaining fiber of claim 3, wherein the air-cladding comprises a single ring of air holes.

4. A polarization maintaining optical fiber comprising:

a fiber core;

an inner cladding surrounding said core, said inner cladding having a cross-section comprising an outer surface having at least three-fold symmetry;

a cladding region disposed about said core and about said inner cladding, said cladding region comprising a plurality of features disposed therein, said plurality of features forming an optical cladding for said core and said inner cladding; and

a plurality of stress producing regions that induce birefringence in said fiber thereby producing polarization maintaining operation.

5. The optical fiber of claim 4, wherein said plurality of features comprise a plurality of holes.

6. The optical fiber of claim 4, wherein said plurality of features comprise a plurality of air-holes.

7. The optical fiber of claim 4, wherein said stress producing regions are disposed substantially symmetrically about said core.

8. The optical fiber of claim 4, wherein said plurality of stress producing regions comprise a pair of stress producing regions disposed on opposite sides of said core.

20. The polarization maintaining optical fiber of claim 4, wherein the fiber core has a diameter >

15 μ

m.

21. The polarization maintaining optical fiber of claim 4, wherein each of said plurality of stress producing regions has a cross-section having an outer surface, and

wherein said outer surface of each of said stress-producing regions is disposed within said outer surface of said inner cladding.

22. The polarization maintaining optical fiber of claim 4, wherein the cladding region comprises a single ring of said features.

9. A polarization maintaining optical fiber comprising:

a fiber core;

a single ring of regions disposed about said core, said regions forming an optical cladding for said core; and

a plurality of stress producing regions that induce birefringence in said fiber thereby producing polarization maintaining operation.

10. The optical fiber of claim 9, wherein said plurality of regions comprise a plurality of holes.

11. The optical fiber of claim 9, wherein said plurality of regions comprise a plurality of air-holes.

12. The optical fiber of claim 9, wherein said stress producing regions are disposed substantially symmetrically about said core.

13. The optical fiber of claim 9, wherein said plurality of stress producing regions comprise a pair of stress producing regions disposed on opposite sides of said core.

23. The polarization maintaining optical fiber of claim 9, wherein the fiber core has a diameter >

15 μ

m.

24. The polarization maintaining optical fiber of claim 9, wherein said plurality of stress producing regions are surrounded by an inner cladding that surrounds said core, and wherein said plurality of regions substantially surrounds said inner cladding.

25. The polarization maintaining optical fiber of claim 9, farther comprising an inner cladding that surrounds said core, wherein said plurality of regions substantially surrounds said inner cladding, and wherein said inner cladding has a cross-section having an outer surface having at least three-fold symmetry.

26. The polarization maintaining optical fiber of claim 9, wherein said fiber core has a first refractive index and said regions in said single ring have a second refractive index, said first refractive index being higher than said second refractive index.