ALL-FIBER CHIRPED PULSE AMPLIFICATION SYSTEMS

• US 20130293947A1
• Filed: 07/08/2013
• Published: 11/07/2013
• Est. Priority Date: 06/03/2003
• Status: Active Grant

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Fermann, Martin E., Imeshev, Gennady, Cho, Gyu C., Liu, Zhenlin, Harter, Donald J.
• Granted Patent: US 9,042,004 B2
• Time in Patent Office: Days
• US Class Current: 359/337
• 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 3/0078 Frequency filtering
• 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 3/06741 Photonic crystal fibre, i.e. the fibre having a photonic bandgap
• CPC Class Codes: H01S 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/06758 Tandem amplifiers
• CPC Class Codes: H01S 3/094007 Cladding pumping, i.e. pump light propagating in a clad surrounding the active core
• CPC Class Codes: H01S 3/1086 using scattering effects, e.g. Raman or Brillouin effect
• CPC Class Codes: H01S 3/1608 erbium
• 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 3/302 in an optical fibre

Abstract

By compensating polarization mode-dispersion as well chromatic dispersion in photonic crystal fiber pulse compressors, high pulse energies can be obtained from all-fiber chirped pulse amplification systems. By inducing third-order dispersion in fiber amplifiers via self-phase modulation, the third-order chromatic dispersion from bulk grating pulse compressors can be compensated and the pulse quality of hybrid fiber/bulk chirped pulse amplification systems can be improved. Finally, by amplifying positively chirped pulses in negative dispersion fiber amplifiers, a low noise wavelength tunable seed source via anti-Stokes frequency shifting can be obtained.

Claims

1. A method for the generation of high quality pulses from a fiber chirped pulse amplification system in the presence of self-phase modulation in the fiber amplifier, comprising:

selecting stretched pulses with an input pulse spectrum into the fiber amplifier such that one or a combination of substantial gain-pulling and gain-narrowing occurs in said amplifier, said gain-pulling manifesting itself in a substantial spectral shift of the average optical frequency of the pulse spectrum, said gain-narrowing manifesting itself in the generation of an amplified pulse spectrum with a spectral width not greater than the input pulse spectrum, wherein the quality of the compressed pulses improves in the presence of self-phase modulation.

2. A method for improving the output pulse quality in high power waveguide chirped pulse amplification systems, comprising:

setting a pulse energy to cause 0.3-10π

level of self-phase modulation in said waveguide chirped pulse amplification system, wherein said pulse energy and self-phase modulation produce improved pulse quality characterizable by at least one of;

(a) a reduction in pulse width, (b) a corresponding increase in the ratio of a compressed pulse width FWHM to energy in the wings of said pulse, and (c) a peak of a correlation signal relative to the energy in the wings of said correlation signal.

3. A method for improving the output pulse quality in high power waveguide chirped pulse amplification systems, in the presence of self-phase modulation in the fiber amplifier, comprising:

selecting stretched pulses with an input pulse spectrum into said fiber amplifier, said input pulse spectrum being conditioned by a seed source and an optical filter inserted between said seed source and said fiber amplifier; and

further selecting the optical bandwidth and center wavelength of said seed source as well as the transmission bandwidth and the center wavelength of said filter such that the quality of the compressed pulses improves in the presence of self-phase modulation.

4. A fiber chirped pulse amplification system, comprising:

a short pulse optical source system capable of producing stretched optical pulses;

a power amplifier receiving said stretched pulses at an input thereof;

and being operable in a large self-phase modulation regime, and producing a pulse output which improves in pulse quality, and whose higher order dispersion varies, with the pulse energy in the system.

5. A fiber chirped pulse amplification system, comprising;

a seed source generating optical pulses;

a pulse stretcher for temporally stretching pulses from said seed source thereby generating chirped optical pulses;

a non-linear amplifier disposed downstream from said pulse stretcher and arranged to receive and amplify chirped optical pulses, said non-linear amplifier configured to generate substantial self-phase modulation and corresponding non-linear phase delay of pulses propagating therein, wherein a spectrum at the output of said non-linear amplifier is characterized by having increased amplitude modulation with an increase in pulse energy; and

a pulse compressor disposed downstream from said non-linear amplifier and arranged to receive amplified chirped pulses and to temporally compress said amplified chirped pulses,

wherein said stretched pulses amplified in said amplifier are subjected to said substantial level of self-phase modulation, and said substantial level of self-phase modulation provides a level of third-order dispersion that at least partially compensates for the level of third-order dispersion from said pulse stretcher and said pulse compressor.

6. The fiber chirped pulse amplification system according to claim 5, wherein said pulse compressor comprises a bulk grating compressor, and said amplification system is arranged to induce third-order dispersion in said non-linear amplifier via self-phase modulation in such a way that third-order chromatic dispersion from said bulk grating pulse compressor is compensated and the pulse quality of compressed pulses output from said bulk grating pulse compressor is improved.

7. The fiber chirped pulse amplification system according to claim 5, wherein said chirped optical pulses accumulate third-order dispersion in the presence of said self-phase modulation, gain-narrowing, gain-pulling and gain depletion in said non-linear amplifier.

8. The fiber chirped pulse amplification system according to claim 5, wherein said chirped pulses are characterized as cubicon pulses which impart controllable levels of at least linear and quadratic pulse chirp in the presence of at least said substantial level of self-phase modulation in such a way that can be at least partially compensated by dispersive delay lines that produce significant levels of second and third-order dispersion as well as higher-order dispersion.

9. The fiber chirped pulse amplification system according to claim 5, wherein said pulse stretcher and said pulse compressor each comprise photonic crystal fiber.

10. The fiber chirped pulse amplification system according to claim 5, wherein said pulse compressor is characterized by having a level of second, third- and higher-order chromatic dispersion, and wherein said non-linear amplifier is a fiber amplifier and is configured such that an output pulse spectrum thereof is wavelength-shifted with respect to said input pulse spectrum.

11. The fiber chirped pulse amplification system according to claim 5, wherein said non-linear amplifier is configured as a cubicon pulse amplifier.

12. The fiber chirped pulse amplification system according to claim 5, wherein said seed source provides sub-10 picosecond pulses.

13. The fiber chirped pulse amplification system according to claim 5, wherein said fiber amplifier is configured such that said chirped pulses produce a nonlinear pulse chirp that is at least partially compensated by the level of third-order dispersion from said pulse stretcher and said pulse compressor.

14. The fiber chirped pulse amplification system according to claim 5, wherein said level of self-phase modulation is in the range of 0.3-10π

.

19. The fiber chirped pulse amplification system according to claim 5, wherein through asymmetric pulse amplitude shaping followed by said self-phase-modulation in said non-linear amplifier, dispersion of an output is controllable.

20. The fiber chirped pulse amplification system according to claim 19, wherein said fiber chirped pulse amplification system comprises a higher order dispersion compensator which includes a pulse stretcher and an amplitude filter which creates a stretched, asymmetrically shaped pulse.

21. The fiber chirped pulse amplification system according to claim 5, wherein the seed source comprises a bulk solid-state mode-locked laser.

22. The fiber chirped pulse amplification system according to claim 5, wherein the seed source comprises a fiber mode-locked laser.

23. The fiber chirped pulse amplification system according to claim 5, wherein said pulses are stretched to a width of approximately 100 ps.

24. The fiber chirped pulse amplification system according to claim 5, wherein an input pulse spectrum to said non-linear amplifier is conditioned by a seed source and an optical filter inserted between said seed source and said non-linear amplifier;

and wherein the optical bandwidth and center wavelength of said seed source as well as the transmission bandwidth and the center wavelength of said filter are selected such that the quality of the compressed pulses improves in the presence of increased self-phase modulation.

25. The fiber chirped pulse amplification system according to claim 5, wherein operation of said non-linear amplifier in said large self-phase modulation regime produces a pulse output which improves pulse quality with an increase in pulse energy, and wherein higher order dispersion varies with pulse energy in the system.

15. A fiber chirped pulse amplification system, comprising;

a seed source;

a pulse stretcher for temporally stretching pulses from said seed source;

a non-linear amplifier configured as a cubicon pulse amplifier; and

a pulse compressor,

wherein the pulses amplified in said non-linear amplifier are subjected to a substantial level of self-phase modulation, and such that there is an observable increase in amplitude modulation of an output spectrum of said pulses as compared to an input spectrum thereof, said amplitude modulation characterized by at least an increase in spectral amplitude ripple with an increase in pulse energy,

wherein pulse quality at an output of said pulse compressor is improved with an increase in pulse energy, notwithstanding said increase in amplitude modulation and ripple in said spectrum.

16. The fiber chirped pulse amplification system according to claim 15, wherein a spectrum at an output of said amplifier is substantially gain narrowed with respect to said input pulse spectrum.

17. A fiber chirped pulse amplification system, comprising:

a short pulse optical source;

a pulse stretcher configured to temporally stretch the pulses from said source;

at least one nonlinear fiber amplifier configured to accept pulses with an input pulse spectrum and emitting amplified pulses with a shifted output pulse spectrum;

a pulse compressor having a level of third-order chromatic dispersion,

said nonlinear fiber amplifier being of a cubicon type which at least partially compensates for the third order dispersion of at least said compressor, and being operable in a large self-phase modulation regime of 0.3-10π

.

18. A fiber chirped pulse amplification system as claimed in claim 17, wherein the nonlinear fiber amplifier comprises a nonlinear undoped fiber and a linear amplifier.