Highly rare-earth-doped optical fibers for fiber lasers and amplifiers

• US 8,902,493 B2
• Filed: 07/16/2013
• Issued: 12/02/2014
• Est. Priority Date: 12/04/2008
• Status: Expired due to Fees

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Dong, Liang, Fermann, Martin E., McKay, Hugh, Fu, Libin, Suzuki, Shigeru
• Primary Examiner(s): Diacou, Ari M
• Application Number:
  US13/943,582
• Publication Number:
  US 20130301115A1
• Time in Patent Office: 504 Days
• Field of Search: 359/341.5, 359/337.3
• US Class Current: 359/337.3
• CPC Class Codes: C03C 13/046 Multicomponent glass compositions
• CPC Class Codes: G02B 2006/12038 Glass (SiO2 based materials)
• CPC Class Codes: G02B 2006/1209 Multimode
• CPC Class Codes: G02B 6/02347 Longitudinal structures arranged to form a regular periodic lattice, e.g. triangular, square, honeycomb unit cell repeated throughout cladding
• 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 6/036 core or cladding comprising multiple layers multicore optical fibres G02B6/02042; microstructured properties G02B6/02295; omniguide fibres G02B6/023
• CPC Class Codes: H01S 2301/03 Suppression of nonlinear conversion, e.g. specific design to suppress for example stimulated brillouin scattering [SBS], mainly in optical fibres in combination with multimode pumping
• 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 3/1603 rare earth
• CPC Class Codes: H01S 3/1616 thulium
• CPC Class Codes: H01S 3/1618 ytterbium
• CPC Class Codes: H01S 3/163 characterised by a crystal matrix
• CPC Class Codes: H01S 3/1691 characterised by additives / sensitisers / promoters as further dopants
• CPC Class Codes: H01S 3/1693 aluminium
• CPC Class Codes: H01S 3/175 phosphate glass
• CPC Class Codes: H01S 3/176 silica or silicate glass
• CPC Class Codes: H04B 10/2507 for the reduction or elimination of distortion or dispersion

Abstract

Various embodiments described herein comprise a laser and/or an amplifier system including a doped gain fiber having ytterbium ions in a phosphosilicate glass. Various embodiments described herein increase pump absorption to at least about 1000 dB/m-9000 dB/m. The use of these gain fibers provide for increased peak-powers and/or pulse energies. The various embodiments of the doped gain fiber having ytterbium ions in a phosphosilicate glass exhibit reduced photo-darkening levels compared to photo-darkening levels obtainable with equivalent doping levels of an ytterbium doped silica fiber.

Claims

1. An optical fiber comprising:

a rare earth doped glass comprising silica, ytterbium, phosphorus, and aluminum,

wherein the concentration of ytterbium in said rare-earth doped glass is in the range from 0.5 to 15 mol % so that said optical fiber is configured to have a peak absorption greater than about 3000 dB/m at a pump wavelength and a gain greater than about 0.5 dB/cm at an emission wavelength,

wherein the concentration of phosphorous in said rare-earth doped glass comprises at least 50 mol % P₂O₅ so that a saturated value of photo-darkening loss in the optical fiber is less than about 10 dB/m at said emission wavelength,

wherein the concentration of aluminum in said rare-earth doped glass is in a range from 0.5 to 15 mol %, and

wherein the concentration of boron in said rare-earth doped glass is in a range from 0 to 25 mol %.

2. The optical fiber of claim 1, wherein said optical fiber is a large-core optical fiber having a core diameter larger than about 30 μ

m.

3. The optical fiber of claim 2, wherein said core diameter is less than about 130 μ

m.

4. The optical fiber of claim 1, wherein said rare-earth doped glass further comprises 0.5 to 1 mol % erbium.

5. The optical fiber of claim 1, wherein the concentration of aluminum in said rare-earth doped glass is in a range from 1 to 10 mol %.

6. The optical fiber of claim 1, wherein the concentration of aluminum in said rare-earth doped glass is in a range from 5 to 10 mol %.

7. The optical fiber of claim 1, wherein the optical fiber is configured to have a gain greater than about 100 dB/m.

8. The optical fiber of claim 1, wherein the optical fiber is configured to have a gain greater than about 500 dB/m.

9. The optical fiber of claim 1, wherein said pump wavelength is in a range from about 0.9 μ

m to about 1.0 μ

m.

10. The optical fiber of claim 1, wherein said emission wavelength is in a range from about 1.0 μ

m to about 1.1 μ

m.

11. The optical fiber of claim 1, wherein the peak absorption is in a range from about 3000 dB/m to about 9000 dB/m.

12. The optical fiber of claim 1, wherein the gain is in a range from about 0.5 dB/cm to about 10 dB/cm.

13. The optical fiber of claim 1, wherein the saturated value of the photo-darkening loss in the optical fiber is less than about 10 dB/m and greater than about 1 dB/m.

14. The optical fiber of claim 1, wherein the concentration of phosphorous in said rare-earth doped glass is less than 65 mol % P₂O₅.

15. An optical amplifier comprising:

a pump source;

a gain fiber; and

a dispersion compensator configured to generate sub-picosecond output pulses,

said gain fiber comprising;

a cladding comprising silica; and

a core comprising silica, ytterbium, phosphorus, and aluminum,

wherein the concentration of ytterbium in said core is in a range from 0.5 to 15 mol % so that said gain fiber has a peak absorption greater than about 3000 dB/m at a pump wavelength and a gain greater than about 0.5 dB/cm at an emission wavelength,

wherein the concentration of phosphorous in said core comprises at least 50 mol % P₂O₅ so that a saturated value of photo-darkening loss of the gain fiber is less than about 10 dB/m at the emission wavelength,

wherein the concentration of aluminum in said core is in a range from 0.5 to 15 mol %, and

wherein the concentration of boron in said core is in a range from 0 to 25 mol %.

16. The optical amplifier of claim 15, wherein said gain fiber is a large-core optical fiber having a core diameter larger than about 30 μ

m.

17. The optical amplifier of claim 16, wherein said core diameter is less than about 130 μ

m.

18. The optical amplifier of claim 15, wherein said gain fiber is configured with a total length sufficiently short to provide a repetition rate in a range of about 100 MHz to about 10 GHz.

19. The optical amplifier of claim 15, wherein said pump source is configured to core pump said gain fiber, and said pump source comprises a large-core fiber amplifier.

20. The optical amplifier of claim 15, wherein said pump source is configured to cladding pump said gain fiber.

21. The optical amplifier of claim 15, wherein said optical amplifier comprises a gain medium having a length in a range of a few centimeters to a few meters, and a gain per unit length in a range of about 0.5 dB/cm to about 10 dB/cm.

22. The optical amplifier of claim 21, wherein said gain per unit length is in the range of about 2 dB/cm to about 10 dB/cm.

23. The optical amplifier of claim 15, wherein said pump wavelength is in a range from about 0.9 μ

m to about 1.0 μ

m.

24. The optical amplifier of claim 15, wherein said emission wavelength is in a range from about 1.0 μ

m to about 1.1 μ

m.

25. The optical amplifier of claim 15, wherein the peak absorption is in a range from about 3000 dB/m to about 9000 dB/m.

26. The optical amplifier of claim 15, wherein the gain is in a range from about 0.5 dB/cm to about 10 dB/cm.

27. The optical amplifier of claim 15, wherein the saturated value of the photo-darkening loss in the gain fiber is less than about 10 dB/m and greater than about 1 dB/m.

28. The optical amplifier of claim 15, wherein the concentration of phosphorous in the core is less than 65 mol % P₂O₅.

29. A fiber laser comprising the optical amplifier of claim 15, said optical amplifier configured as a gain medium within an optical resonator.

30. The fiber laser of claim 29, wherein said gain fiber has a length in a range from about 1 mm to about 20 cm.