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

• US 7,394,591 B2
• Filed: 10/12/2004
• Issued: 07/01/2008
• 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: Harter, Donald J., Cho, Gyu C., Fermann, Martin E., Hartl, Ingmar
• Primary Examiner(s): Keith; Jack W.
• Assistant Examiner(s): BOLDA, ERIC L
• Application Number:
  US10/960,923
• Publication Number:
  US 20050111500A1
• Time in Patent Office: 1,358 Days
• Field of Search: 359/348, 359/341.1, 359/341, 359/1
• 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 laser apparatus, comprising:

a laser pulse source comprising a mode-locked fiber laser;

a first pulse stretcher configured for stretching said laser pulses to produce one or more stretched laser pulses;

an amplifier configured to receive each of said stretched pulses to produce amplified stretched pulses, wherein said amplifier comprises at least a regenerative amplifier; and

a pulse compressor configured for producing one or more compressed amplified laser pulses obtained from stretched amplified laser pulses, the apparatus further including;

a second pulse stretcher coupled to said laser pulse source; and

a fiber amplifier coupled to said second pulse stretcher and said first pulse stretcher.

2. The laser apparatus of claim 1, wherein said mode-locked fiber laser is based on at least ytterbium, neodymium or erbium.

3. The laser apparatus of claim 1, wherein said second pulse stretcher comprises polarization-maintaining fiber with sufficient positive dispersion to stretch said laser pulses.

4. The laser apparatus of claim 1, wherein said pulse compressor compensates for dispersion caused by said first and second pulse stretchers, said regenerative amplifier and said fiber amplifier.

5. The laser apparatus of claim 1, wherein said fiber amplifier comprises a Yb:

or Nd;

amplifier.

6. The laser apparatus of claim 1 wherein at least one of said first and second stretchers comprise a dispersion compensator to compensate a dispersion of at least said pulse compressor.

7. The laser apparatus of claim 6 wherein said dispersion compensator further compensates dispersion of said laser apparatus so as produce a transform limited output pulse at an output of said compressor.

8. The laser apparatus of claim 6 wherein said dispersion compensator comprises at least one of a fiber and a combination of fibers having a different dispersion.

9. The laser apparatus of claim 6 wherein said dispersion compensator comprises a non-linear chirped fiber grating.

10. The laser apparatus of claim 1 wherein said one or more compressed amplified pulses comprises a pulse width of about 1 picosecond.

11. A laser method for material processing, comprising:

producing a plurality of laser pulses;

optically stretching said laser pulses;

amplifying a predetermined energy of each of said optically stretched laser pulses, wherein a fiber amplifier produces first amplified pulses;

optically stretching said first amplified pulses;

amplifying the energy of each of said first amplified laser pulses, wherein a regenerative amplifier produces second amplified pulses;

optically compressing said second amplified pulses to produce amplified compressed pulses; and

outputting said amplified compressed pulses and delivering at least one pulse to a workpiece to process at least a portion of said workpiece.

12. The laser method of claim 11, wherein said optical compression of said second amplified pulses compensates for dispersion caused by stretching of said pulses in said regenerative amplifier.