Asymmetrical distributed feedback fiber laser

• US 6,188,712 B1
• Filed: 08/09/1999
• Issued: 02/13/2001
• Est. Priority Date: 11/04/1998
• Status: Expired due to Fees

• Current Assignee: Optigain, Inc. (Furukawa Electric Company Limited)
• Original Assignee: Optigain, Inc. (Furukawa Electric Company Limited)
• Inventors: Krishnan, Mala, Jiang, Shijun, Bastien, Steven P.
• Primary Examiner(s): Lee, John D.
• Application Number:
  US09/370,444
• Time in Patent Office: 554 Days
• Field of Search: 385/37, 372/6, 372/92, 372/95, 372/96, 372/98, 372/102, 372/106
• US Class Current: 372/96
• CPC Class Codes: H01S 3/0675 Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers

Abstract

A DFB fiber laser comprises a single-mode, rare-earth doped optical fiber having a uniform Bragg grating with a reflectivity of about 90%, and a single-mode, hi-birefringent optical fiber having a uniform Bragg grating with a reflectivity of near 100%. The output end of the hi-bi fiber is coupled to the input end of the doped fiber to form an asymmetrical fiber laser cavity. The input end of the hi-bi fiber is pumped by a light source (laser diode) having a wavelength in the absorption range of the doped fiber. Pump light entering the hi-bi fiber is passed into the doped fiber to produce a stimulated output. The hi-bi fiber provides single polarization operation, acts as an end reflector to provide single longitudinal mode operation in the laser cavity while also providing single sided output.

Claims

1. An asymmetrical DFB fiber laser assembly comprising:

a single-mode, rare-earth doped optical fiber having a grating, said grating having a reflectivity which is less than 100%;

a hi-birefringent, single mode optical fiber having an input end and an output end that is coupled to an input end of said single-mode rare-earth doped optical fiber, said hi-birefringent, single mode optical fiber having a grating, said grating having a substantially 100% reflectivity; and

a light source coupled to said input end of said hi-birefringent, single mode optical fiber, said light source having an output wavelength within the rare-earth absorption spectrum.

2. The asymmetrical DFB fiber laser assembly of claim 1 wherein said output end of said hi-birefringent, single mode optical fiber is coupled to said input end of said single-mode rare-earth doped optical fiber by a splice.

3. The asymmetrical DFB fiber laser assembly of claim 1 wherein said output end of said hi-birefringent, single mode optical fiber is coupled to said input end of said single-mode rare-earth doped optical fiber by a mechanical coupler.

4. The asymmetrical DFB fiber laser assembly of claim 1 wherein said light source comprises a semiconductor laser diode.

5. The asymmetrical DFB fiber laser assembly of claim 1 wherein said single-mode, rare-earth doped optical fiber has a reflectivity of about 90%.

6. The asymmetrical DFB fiber laser assembly of claim 5 wherein said hi-birefringent single mode optical fiber has a length of between about 0.1 cm and about 1.0 cm.

7. The asymmetrical DFB fiber laser assembly of claim 6 wherein said hi-birefringent, single mode optical fiber has a length of about 0.5 cm.

8. The asymmetrical DFB fiber laser assembly of claim 6 wherein a combined length of the hi-birefringent, single mode optical fiber, and the single-mode rare-earth doped optical fiber is between about 4.0 cm and about 8.0 cm.

9. The asymmetrical DFB fiber laser assembly of claim 5 wherein said single mode, rare-earth doped optical fiber has a length of between about 2.0 and about 6.0 cm.

10. The asymmetrical DFB fiber laser assembly of claim 9 wherein a combined length of the hi-birefringent, single mode optical fiber, and the single-mode rare-earth doped optical fiber is between about 4.0 cm and about 8.0 cm.

11. The asymmetrical DFB fiber laser assembly of claim 5 wherein a combined length of the hi-birefringent, single mode optical fiber, and the single-mode rare-earth doped optical fiber is between about 4.0 cm and about 8.0 cm.

12. The asymmetrical DFB fiber laser assembly of claim 1 wherein said hi-birefringent, single mode optical fiber has a length of between about 0.1 cm and about 1.0 cm.

13. The asymmetrical DFB fiber laser assembly of claim 12 wherein said hi-birefringent, single mode optical fiber has a length of about 0.5 cm.

14. The asymmetrical DFB fiber laser assembly of claim 12 wherein said single mode, rare-earth doped optical fiber has a length of between about 2.0 and about 6.0 cm.

15. The asymmetrical DFB fiber laser assembly of claim 12 wherein a combined length of the hi-birefringent, single mode optical fiber, and the single, mode rare-earth doped optical fiber is between about 4.0 cm and about 8.0 cm.

16. The asymmetrical DFB fiber laser assembly of claim 1 wherein said single mode, rare-earth doped optical fiber has a length of between about 2.0 and about 6.0 cm.

17. The asymmetrical DFB fiber laser assembly of claim 16 wherein a combined length of the hi-birefringent, single mode optical fiber, and the single-mode rare-earth doped optical fiber is between about 4.0 cm and about 8.0 cm.

18. The asymmetrical DFB fiber laser assembly of claim 1 wherein a combined length of the hi-birefringent, single mode optical fiber, and the single-mode rare-earth doped optical fiber is between about 4.0 cm and about 8.0 cm.

19. The asymmetrical DFB fiber laser assembly of claim 1 further comprising an optical isolator coupled to an output end of said hi-birefringent, single mode optical fiber.

20. The asymmetrical DFB fiber laser assembly of claim 19 further comprising a feedback loop to stabilize output power.

21. The asymmetrical DFB fiber laser assembly of claim 1 further comprising a feedback loop to stabilize output power.