Compact, coherent, high brightness light sources for the mid and far IR

• US 8,787,410 B2
• Filed: 02/14/2011
• Issued: 07/22/2014
• Est. Priority Date: 02/14/2011
• Status: Active Grant

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Fermann, Martin
• Primary Examiner(s): Stultz, Jessica
• Assistant Examiner(s): CARTER, MICHAEL W
• Application Number:
  US13/026,762
• Publication Number:
  US 20120205352A1
• Time in Patent Office: 1,254 Days
• Field of Search: 372/6
• US Class Current: 372/6
• CPC Class Codes: B23K 26/352 for surface treatment
• CPC Class Codes: B23K 26/361 for deburring or mechanical trimming B23K26/351 takes precedence
• CPC Class Codes: B23K 26/362 Laser etching
• 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 3/0675 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 3/06791 Fibre ring lasers fibre laser gyrometers G01C19/72
• CPC Class Codes: H01S 3/10015 by monitoring or controlling, e.g. attenuating, the input signal
• CPC Class Codes: H01S 3/10092 Coherent seed, e.g. injection locking
• CPC Class Codes: H01S 3/1112 Passive mode locking
• CPC Class Codes: H01S 3/1118 Semiconductor saturable absorbers, e.g. semiconductor saturable absorber mirrors [SESAMs]; Solid-state saturable absorbers, e.g. carbon nanotube [CNT] based
• CPC Class Codes: H01S 3/1608 erbium
• CPC Class Codes: H01S 3/1616 thulium

Abstract

Compact high brightness light sources for the mid and far IR spectral region, and exemplary applications are disclosed based on passively mode locked Tm fiber comb lasers. In at least one embodiment the coherence of the comb sources is increased in a system utilizing an amplified single-frequency laser to pump the Tm fiber comb laser. The optical bandwidth generated by the passively mode locked Tm fiber comb laser is further decreased by using simultaneous 2^nd and 3^rd order dispersion compensation using either appropriate chirped fiber Bragg gratings for dispersion compensation, or fibers with appropriately selected values of 2^nd and 3^rd order dispersion. Fibers with large anomalous values of third order dispersion, or fibers with large numerical apertures, for example fibers having air-holes formed in the fiber cladding may be utilized.

Claims

1. A fiber-laser based, chirped pulse amplification system, comprising:

a passively mode locked fiber oscillator operating at or near a wavelength of 2000 nm;

a pulse stretcher receiving pulses from said passively mode locked fiber oscillator and producing stretched pulses;

a fiber amplifier amplifying said stretched pulses and producing stretched and amplified pulses;

a linear pulse compressor to compress said stretched and amplified pulses; and

a large mode area fiber configured to nonlinearly compress the pulses output from the linear pulse compressor so as to further compress the pulses via Raman-soliton generation or higher order soliton compression.

2. The fiber-laser based, chirped pulse amplification system according to claim 1, further comprising a stretcher fiber arrangement with overall positive dispersion and anomalous third order dispersion at a wavelength of operation of said passively mode locked fiber oscillator.

3. The fiber-laser based, chirped pulse amplification system according to claim 1, further comprising a pulse compressor having a least one of a bulk GRISM, prism, grating and glass plate.

4. The fiber-laser based, chirped pulse amplification system according to claim 1, wherein an output of said system pumps an optical parametric oscillator, generator or amplifier.

5. The fiber-laser based, chirped pulse amplification system according to claim 1, wherein an output of said system is capable of generating self-frequency shifting in a nonlinear crystal or waveguide.

6. The fiber-laser based, chirped pulse amplification system according to claim 1, further comprising an optical modulator inserted upstream from said fiber amplifier to reduce the pulse repetition rate of the pulses being amplified in said fiber amplifier.

7. A-fiber-laser based amplification system, comprising:

a passively mode locked fiber oscillator operating at or near a wavelength of 2000 nm;

a fiber pulse stretcher receiving pulses from said passively mode locked fiber oscillator and producing stretched pulses, said fiber pulse stretcher providing anomalous third order dispersion in the wavelength operation range of said oscillator; and

a fiber amplifier amplifying said stretched pulses and producing recompressed and amplified pulses at an output thereof,

wherein second and third order dispersion of said fiber-based amplification system are at least partially compensated by said anomalous dispersion provided with said pulse stretcher.

8. A fiber-laser based amplification system according to claim 7, wherein said amplifier is nonlinear and provides a value of self-phase modulation of at least 2.

9. A fiber-laser based amplification system according to claim 8, wherein the spectrum at the output of said amplifier is broadened due to said self-phase modulation.

10. A fiber-laser based amplification system according to claim 8, wherein the pulses at the output of said amplifier are nonlinearly compressed due to said self-phase modulation.

11. A fiber-laser based amplification system, according to claim 7, further comprising a highly nonlinear fiber directly spliced to the output of said amplifier.

12. A fiber-laser based amplification system according to claim 11, further comprising an undoped fiber directly spliced to the output of said amplifier.

13. A fiber-laser based amplification system according to claim 7, further comprising an undoped fiber directly spliced to the output of said amplifier.

14. A fiber-laser based amplification system according to claim 13, wherein said undoped fiber is nonlinear and provides a value of self-phase modulation of at least 2.

15. A fiber-laser based amplification system, according to claim 7, wherein said fiber stretcher comprises a Germania doped fiber.

16. A fiber-laser based amplification system, according to claim 7, wherein said fiber stretcher comprises a fiber having a numerical aperture greater than about 0.25 and up to about 0.4.

17. A fiber-laser based amplification system, according to claim 7, wherein said fiber stretcher comprises a fiber having an air-hole formed in the fiber cladding.

18. A fiber-laser based amplification system, comprising:

a passively mode locked fiber oscillator operating at a wavelength at or near 2000 nm;

a fiber pulse stretcher receiving pulses from said passively mode locked fiber oscillator and producing stretched pulses, said fiber pulse stretcher providing anomalous third order dispersion in the wavelength operation range of said oscillator;

a fiber amplifier amplifying said stretched pulses and producing recompressed and amplified pulses at an output thereof; and

a highly nonlinear fiber spliced directly to the output of said amplifier, said highly nonlinear fiber producing an optical continuum.

19. A fiber-laser based amplification system according to claim 18, further comprising an undoped fiber inserted upstream of said highly nonlinear fiber.