Utilization of Yb: and Nd: mode-locked oscillators in solid-state short pulse laser systems

• US 7,929,203 B2
• Filed: 06/03/2008
• Issued: 04/19/2011
• Est. Priority Date: 05/23/2000
• Status: Expired due to Fees

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Hartl, Ingmar, Harter, Donald J., Cho, Gyu C., Fermann, Martin E.
• Primary Examiner(s): BOLDA, ERIC L
• Application Number:
  US12/132,364
• Publication Number:
  US 20080232407A1
• Time in Patent Office: 1,050 Days
• Field of Search: 359/341.5, 359/348, 372/25
• US Class Current: 359/348
• 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 3/0078 Frequency filtering
• CPC Class Codes: H01S 3/0085 Modulating the output, i.e. the laser beam is modulated outside the laser cavity
• CPC Class Codes: H01S 3/067 Fibre lasers
• CPC Class Codes: H01S 3/0675 Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers
• CPC Class Codes: H01S 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/094042 of a fibre laser
• CPC Class Codes: H01S 3/10023 by functional association of additional optical elements, e.g. filters, gratings, reflectors
• CPC Class Codes: H01S 3/109 Frequency multiplication, e.g. harmonic generation
• CPC Class Codes: H01S 3/1616 thulium
• CPC Class Codes: H01S 3/1618 ytterbium
• CPC Class Codes: H01S 3/1643 YAG
• CPC Class Codes: H01S 3/235 Regenerative amplifiers
• CPC Class Codes: H01S 5/5045 the arrangement having a frequency filtering function

Abstract

An optimized Yb: doped fiber mode-locked oscillator and fiber amplifier system for seeding Nd: or Yb: doped regenerative amplifiers. The pulses are generated in the Yb: or Nd: doped fiber mode-locked oscillator, and may undergo spectral narrowing or broadening, wavelength converting, temporal pulse compression or stretching, pulse attenuation and/or lowering the repetition rate of the pulse train. The conditioned pulses are subsequently coupled into an Yb: or Nd: fiber amplifier. The amplified pulses are stretched before amplification in the regenerative amplifier that is based on an Nd: or Yb: doped solid-state laser material, and then recompressed for output.

Claims

1. A mode locked laser system for seeding a regenerative amplifier, comprising:

a source of laser pulses comprising a fiber laser;

a Yb;

fiber amplifier for amplifying said pulses; and

a regenerative amplifier based on Nd;

or Yb;

or Ti;

Al₂O₃ materials for receiving said amplified pulses as seed pulses, wherein at least one of said pulse source and said Yb;

fiber amplifier includes means for controlling a bandwidth and a spectral center of its output to match that of said regenerative amplifier, and wherein said means for controlling comprises a co-propagating pump laser and a counter-propagating pump laser pumped so as to induce a frequency shift in said fiber laser.

2. The system of claim 1, wherein said Yb:

fiber amplifier comprises a tuner for determining the output bandwidth and spectral width thereof.

3. A mode locked laser system for seeding a regenerative amplifier, comprising:

a source of laser pulses;

a fiber amplifier for amplifying said pulses; and

a regenerative amplifier based on Nd;

or Yb;

materials for receiving said amplified pulses as seed pulses; and

means for maintaining the output wavelength of the regenerative amplifier in the presence of substantial spectral shifting in the amplification of the seed pulses, comprising means for increasing input energy of said seed pulses, or for frequency-shifting said seed pulses, wherein said means for frequency shifting comprises a co-propagating pump laser and a counter-propagating pump laser coupled to said fiber amplifier that induces said frequency shift of pulses propagating in said fiber amplifier.

4. The mode locked laser system for seeding a regenerative amplifier of claim 3, wherein said system comprises at least one AOM between said source of laser pulses and said regenerative amplifier, said AOM configured as a variable attenuator.

5. A mode locked laser system for seeding a regenerative amplifier, comprising:

a source of laser pulses;

a fiber amplifier for amplifying said pulses; and

a regenerative amplifier based on Nd;

or Yb;

materials for receiving said amplified pulses as seed pulses; and

means for maintaining the output wavelength of the regenerative amplifier in the presence of substantial spectral shifting in the amplification of the seed pulses, comprising means for increasing input energy of said seed pulses, or for frequency-shifting said seed pulses, wherein said means for frequency shifting comprises a length of optical fiber.

6. The mode locked laser system for seeding a regenerative amplifier of claim 5, wherein said system comprises at least one AOM between said source of laser pulses and said regenerative amplifier, said AOM configured as a variable attenuator.

7. A mode locked laser system for seeding a regenerative amplifier, comprising:

a source of laser pulses;

a Yb;

fiber amplifier for amplifying said pulses;

a regenerative amplifier based on Nd;

or Yb;

materials for receiving said amplified pulses as seed pulses; and

a tuner, comprising a length of optical fiber disposed upstream from said regenerative amplifier, said tuner controlling at least one of a central wavelength and spectral width of said amplified pulses in such a way that controls a spectral characteristic of pulses output from said regenerative amplifier.

8. The mode locked laser system of claim 7, wherein said Yb:

fiber amplifier is pumped by a co-propagating pump laser and a counter-propagating pump laser to tune said source wavelength to said regenerative amplifier wavelength.

9. The mode locked laser system of claim 7, wherein said Yb:

fiber amplifier is controlled to cause a frequency shift such that said source wavelength is tuned to said regenerative amplifier wavelength.

10. The mode locked laser system of claim 7, wherein said Yb:

fiber amplifier is controlled to cause a frequency shift to spectrally narrow said laser pulses output from said source.

11. The mode locked laser system of claim 7, wherein said Yb:

fiber amplifier comprises a multimode fiber amplifier.

12. The mode locked laser system of claim 11, wherein said multimode fiber amplifier comprises a multimode photonic crystal fiber amplifier.

13. The mode locked laser system for seeding a regenerative amplifier of claim 7, wherein said source of laser pulses comprises a mode locked Yb:

fiber oscillator.

14. The mode locked laser system for seeding a regenerative amplifier of claim 7, wherein said tuner comprises at least a portion of said Yb:

fiber amplifier upstream from said regenerative amplifier.

15. The mode locked laser system for seeding a regenerative amplifier of claim 7, further comprising:

a first pulse stretcher configured for stretching pulses from said source to produce one or more stretched pulses, at least a portion of said stretcher comprising a length of optical fiber, said pulse stretcher disposed between said source and said regenerative amplifier, said regenerative amplifier receiving and amplifying said one or more stretched pulses to produce stretched and amplified optical pulses;

a first pulse compressor disposed downstream from said regenerative amplifier, and configured to compress said one or more stretched and amplified optical pulses.

16. The mode locked laser system for seeding a regenerative amplifier of claim 15, at least a portion of said stretcher comprising a length of passive optical fiber.

17. The mode locked laser system for seeding a regenerative amplifier of claim 15, wherein said stretcher comprises a chirped fiber Bragg grating.