Optical pulse source

• US 8,724,215 B2
• Filed: 03/12/2013
• Issued: 05/13/2014
• Est. Priority Date: 01/20/2006
• Status: Active Grant

• Current Assignee: NKT Photonics A/S (NKT A/S)
• Original Assignee: Fianium Ltd (NKT A/S)
• Inventors: Clowes, John Redvers, Grudinin, Anatoly Borisovich, Godfrey, Ian Michael, Vysniauskas, Kestutis
• Primary Examiner(s): Hellner, Mark
• Assistant Examiner(s): Diacou, Ari M
• Application Number:
  US13/797,665
• Publication Number:
  US 20130271824A1
• Time in Patent Office: 427 Days
• Field of Search: 359/346, 359/341.32, 359/341.33, 372/6
• US Class Current: 359/346
• CPC Class Codes: G02F 1/383 of the optical fibre type
• 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 3/005 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 3/0064 Anti-reflection devices, e.g. optical isolaters absorbing layers for marking or protecting purposes in laser working B23K26/50; magneto-optical non-reciprocal devices G02F1/093, G02F1/0955
• 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 3/061 with elliptical or circular cross-section and elongated shape, e.g. rod
• CPC Class Codes: H01S 3/067 Fibre lasers
• CPC Class Codes: H01S 3/06712 Polarising fibre; Polariser
• CPC Class Codes: H01S 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/06758 Tandem amplifiers
• CPC Class Codes: H01S 3/109 Frequency multiplication, e.g. harmonic generation
• CPC Class Codes: H01S 3/1106 Mode locking
• CPC Class Codes: H01S 3/1618 ytterbium
• CPC Class Codes: H01S 3/2308 Amplifier arrangements, e.g. MOPA
• CPC Class Codes: H01S 3/2316 Cascaded amplifiers
• CPC Class Codes: H01S 3/2375 Hybrid lasers H01S3/07 takes precedence

Abstract

The invention can include an apparatus for producing optical pulses, comprising an oscillator for producing optical pulses at a first optical pulse repetition frequency, the optical pulses having a first wavelength; a first optical fiber amplifier; a second optical fiber amplifier; a pulse picker located between the first and second optical fiber amplifiers, the pulse picker operable to reduce the optical pulse repetition frequency of optical pulses, wherein the first amplifier amplifies optical pulses at the first optical pulse repetition frequency and the second amplifier amplifies optical pulses at a reduced optical pulse repetition frequency that is less than the first optical pulse repetition frequency; a nonlinear optical fiber receiving amplified optical pulses having the reduced optical pulse repetition frequency and the first wavelength to produce, at the reduced optical pulse frequency, optical pulses that include one or more nonlinearly produced wavelengths different than the first wavelength; and wherein the pulse picker and the first and second optical fiber amplifiers are located between the oscillator and the nonlinear optical fiber.

Claims

1. Apparatus for producing optical pulses, comprising:

an oscillator for producing optical pulses at a first optical pulse repetition frequency, the optical pulses having a first wavelength;

a first optical fiber amplifier;

a second optical fiber amplifier;

a pulse picker, located between the first and second optical fiber amplifiers, said pulse picker operable to reduce the optical pulse repetition frequency of optical pulses, wherein said first amplifier amplifies optical pulses at the first optical pulse repetition frequency and said second amplifier amplifies optical pulses at a reduced optical pulse repetition frequency that is less than said first optical pulse repetition frequency;

a nonlinear optical fiber receiving amplified optical pulses having the reduced optical pulse repetition frequency and the first wavelength to produce, at the reduced optical pulse frequency, optical pulses that include one or more nonlinearly produced wavelengths different than the first wavelength; and

wherein said pulse picker and said first and second optical fiber amplifiers are located between the oscillator and the nonlinear optical fiber.

2. The apparatus of claim 1 wherein said first optical fiber amplifier comprises an Ytterbium doped fiber amplifier.

3. The apparatus of claim 2 wherein said second optical fiber amplifier comprises an Ytterbium doped fiber amplifier.

4. The apparatus of claim 3 wherein said second optical fiber amplifier comprises a polarization maintaining, single mode fiber amplifier.

5. The apparatus of claim 1 wherein said pulse picker comprises an acousto optic modulator driven at a synchronized gating frequency lower than first optical pulse repetition frequency of the oscillator.

6. The apparatus of claim 1 wherein said oscillator comprises a modelocked fiber oscillator.

7. The apparatus of claim 1 wherein said one or more wavelengths comprises a wavelength that is shorter than said first wavelength.

8. The apparatus of claim 7 wherein said first wavelength has a corresponding frequency and wherein said wavelength that is shorter than said first wavelength has a corresponding frequency that is twice the frequency that corresponds to the first wavelength.

9. The apparatus of claim 1 wherein said optical pulses produced by said oscillator have a first time duration and wherein said amplified optical pulses received by said nonlinear optical fiber have the first time duration.

20. The apparatus of claim 1 comprising a nonlinear optical crystal.

21. The apparatus of claim 20 wherein said nonlinear optical crystal produces optical pulses comprising UV light.

22. The apparatus of claim 20 wherein said nonlinear optical crystal produces optical pulses having a wavelength that is an harmonic of a wavelength of the one or more wavelengths.

23. The apparatus of claim 20 wherein the optical pulses that include one or more nonlinearly produced wavelengths have a time duration less than 10 ns.

10. Method of producing optical pulses, comprising:

producing optical pulses at a first optical pulse repetition frequency, the optical pulses having a first wavelength;

amplifying at the first optical pulse repetition frequency optical pulses having the first wavelength;

pulse picking the amplified optical pulses to produce optical pulses having the first wavelength at a reduced optical frequency that is less than the first optical pulse repetition frequency;

amplifying optical pulses having the first wavelength and the reduced optical pulse repetition frequency; and

nonlinearly producing, responsive to the amplifying of the pulses having the first wavelength and the reduced optical pulse repetition frequency, optical pulses at the reduced optical pulse repetition frequency and including one or more non-linearly produced wavelengths different from the first wavelength.

11. The method of claim 10 wherein the one or more wavelengths different from the first wavelength comprises a wavelength that is shorter than the first wavelength.

12. The method of claim 11 wherein the first wavelength has a corresponding frequency and wherein the wavelength that is shorter than said first wavelength has a corresponding frequency that is twice the frequency that corresponds to the first wavelength.

13. The method of claim 10 comprising separating a desired wavelength of the one or more wavelengths from another wavelength and transmitting light having the desired wavelength as the output of the optical pulse source.

14. The method of claim 10 wherein producing the optical pulses at a first optical pulse repetition frequency and having a first wavelength comprises producing the optical pulses to as to have a first time duration;

and

wherein nonlinearly producing, responsive to the amplifying of the pulses having the first wavelength and the reduced optical pulse repetition frequency comprises nonlinearly producing responsive to the amplifying of the pulses having the first time duration as well as the first wavelength and the reduced optical pulse repetition frequency.

15. The method of claim 10 wherein nonlinearly producing comprises nonlinearly producing with an optical fiber that receives pulses having the first wavelength and the reduced optical pulse repetition frequency.

16. The method of claim 10 wherein nonlinearly producing comprises nonlinearly producing optical pulses to provide first nonlinearly produced optical pulses and then further nonlinearly producing optical pulses from the first nonlinearly produced optical pulses.

17. The method of claim 10 wherein the further nonlinearly produced optical pulses comprise UV light.

18. The method of claim 15 wherein nonlinearly producing comprises nonlinearly producing to provide first nonlinearly produced optical pulses and then further nonlinearly producing, using an optical crystal, optical pulses from the first nonlinearly produced optical pulses.

19. The method of claim 18 wherein the further nonlinearly produced optical pulses comprise UV light.