Sources of, and methods for generating, optical pulses

• US 20020168161A1
• Filed: 04/10/2002
• Published: 11/14/2002
• Est. Priority Date: 04/11/2001
• Status: Active Grant

• Current Assignee: University of Southampton
• Original Assignee: University of Southampton
• Inventors: Monro, Tanya, Price, Jonathan Hugh Vaughan, Richardson, David John, Furasawa, Kentaro
• Granted Patent: US 6,813,429 B2
• Time in Patent Office: Days
• US Class Current: 385/123
• CPC Class Codes: G02F 1/3513 Soliton propagation
• CPC Class Codes: H01S 2301/085 solitons
• 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

Abstract

A source of optical pulses, comprises an optical source operable to generate ultrashort optical pulses at a first wavelength; and an optical fiber amplifier comprising an optical fiber having a core containing a dopant to provide optical gain at the first wavelength, and anomalous dispersion over a wavelength range including the first wavelength and a second wavelength. The optical fiber receives the ultrashort optical pulses, amplifies the ultrashort optical pulses, and alters the wavelength of the ultrashort optical pulses to at least the second wavelength by the soliton-self-frequency shifting effect. Microstructured and/or tapered fibers can be used to provide the required dispersion characteristics. Pulses can be generated in one of three spectral regimes-monocolor solitons, multicolor solitons and continuous broadband spectra by adjusting the energy of the optical pulses, and tunability can be achieved by varying the power of pump light provided to the amplifier.

Claims

1. A source of optical pulses, comprising:

an optical source operable to generate ultrashort optical pulses at a first wavelength; and

an optical fiber amplifier comprising an optical fiber and a pump source operable to deliver pump radiation to the optical fiber, the optical fiber having a core containing a dopant to provide optical gain at the first wavelength, and anomalous dispersion over a wavelength range including the first wavelength and a second wavelength, and being arranged to receive the ultrashort optical pulses, amplify the ultrashort optical pulses, and alter the wavelength of the ultrashort optical pulses to at least the second wavelength by the soliton-self-frequency shifting effect.

2. A source of optical pulses according to claim 1, in which the optical fiber is configured as a microstructured fiber containing an array of air holes running along the length of the fiber.

3. A source of optical pulses according to claim 1, in which the optical fiber is configured as a tapered fiber.

4. A source of optical pulses according to claim 1, in which the dopant comprises ytterbium ions, to provide optical gain at a wavelength of approximately 1 μ

m.

5. A source of optical pulses according to claim 1, in which the dopant comprises ions of one or more of erbium, neodymium, ytterbium, holmium, thulium, praseodymium, germanium, aluminium, boron, samarium, lead and tin.

6. A source of optical pulses according to claim 1, in which the optical source comprises a laser having an optical gain medium in the form of an optical fiber.

7. A source of optical pulses according to claim 6, in which the laser has an optical gain medium comprising an optical fiber doped with ions of ytterbium and operable to generate ultrashort optical pulses at a wavelength of approximately 1 μ

m.

8. A source of optical pulses according to claim 1, in which the pump radiation delivered to the optical fiber can be varied in power, so as to vary the second wavelength within the wavelength range of the anomalous dispersion of the optical fiber of the optical fiber amplifier.

9. A source of optical pulses according to claim 1, in which the ultrashort optical pulses are delivered to the optical fiber of the optical fiber amplifier with sufficient power for the soliton-self-frequency shifting effect to alter the wavelength of the ultrashort pulses to the second wavelength and to one or more additional wavelengths within the wavelength range of the anomalous dispersion of the optical fiber of the optical fiber amplifier.

10. A source of optical pulses according to claim 1, in which the ultrashort optical pulses are delivered to the optical fiber of the optical fiber amplifier with sufficient power for the soliton-self-frequency shifting effect to alter the wavelength of the ultrashort pulses to a broadband continuous spectrum.

11. A source of optical pulses according to claim 1, and further comprising an optical pre-amplifier operable to receive the ultrashort optical pulses from the optical source and amplify the ultrashort optical pulses before the ultrashort optical pulses are received by the optical fiber of the optical fiber amplifier.

12. A source of optical pulses according to claim 11, in which the optical pre-amplifier comprises an optical fibre amplifier.

13. A source of optical pulses according to claim 11, in which the optical pre-amplifier comprises a bulk optic amplifier.

15. A method of producing optical pulses according to claim 14, and further comprising varying an amount of pump radiation delivered to the optical fiber amplifier so as to vary the second wavelength

16. A method of producing optical pulses according to claim 14, in which the optical fiber of the optical fiber amplifier is configured as a microstructured fiber containing an array of air holes running along the length of the fiber.

17. A method of producing optical pulses according to claim 14, in which the optical fiber of the optical fiber amplifier is configured as a tapered fiber.

18. A method of producing optical pulses according to claim 14, in which the ultrashort optical pulses are generated from a laser having an optical gain medium in the form of an optical fiber.

19. A method of producing optical pulses according to claim 18, in which the ultrashort pulses are generated at a wavelength of approximately 1 μ

m from a laser having an optical gain medium in the form of an optical fiber doped with ions of ytterbium.

20. A method of producing optical pulses according to claim 14, and further comprising delivering the ultrashort optical pulses to the optical fiber amplifier with sufficient power for the soliton-self-frequency shifting effect to alter the wavelength of the ultrashort pulses to the second wavelength and to one or more additional wavelengths within the wavelength range of the anomalous dispersion of the optical fiber of the optical fiber amplifier.

21. A method of producing optical pulses according to claim 14, and further comprising delivering the ultrashort optical pulses to the optical fiber amplifier with sufficient power for the soliton-self-frequency shifting effect to alter the wavelength of the ultrashort pulses to a broadband continuous spectrum.

22. A method of producing optical pulses according to claim 14, and further comprising amplifying the ultrashort optical pulses in an optical pre-amplifier before amplifying the ultrashort optical pulses and altering the wavelength of the ultrashort optical pulses in the optical fiber amplifier.

23. A method of producing optical pulses according to claim 22, in which the optical pre-amplifier comprises an optical fibre amplifier.

24. A method of producing optical pulses according to claim 22, in which the optical pre-amplifier comprises a bulk optical amplifier.

14. A method of producing optical pulses, comprising

generating ultrashort optical pulses at a first wavelength;

amplifying the ultrashort optical pulses in an optical fiber amplifier; and

altering the wavelength of the ultrashort optical pulses from the first wavelength to at least a second wavelength by the soliton-self-frequency shifting effect within the optical fiber amplifier;

the optical fiber amplifier comprising an optical fiber having a core containing a dopant to provide optical gain at the first wavelength, and anomalous dispersion over a wavelength range including the first wavelength and a second wavelength.