Single pass laser amplifier with pulsed pumping

Patent metadata

Field	Value
Publication number	US-10216063-B2
Application number	US-201615565626-A
Country	US
Kind code	B2
Filing date	Sep 30, 2016
Priority date	Oct 6, 2015
Publication date	Feb 26, 2019
Grant date	Feb 26, 2019

Abstract

Systems and methods for spectrally broadening seed pulses with a single pass laser amplifier are disclosed. A bulk TM:II-VI polycrystalline material with combined gain and nonlinear characteristic provides passive (cold) spectral broadening of high power seed pulses. Continuous pumping provides more significant spectral broadening. In particular, pulsed pumping of TM:II-VI polycrystalline material (e.g. Cr2+:ZnS, Cr2+:ZnSe, and Cr2+:CdSe) is shown to provide significant spectral broadening to the super continuum generation SCG level. Pulse picking, pump sources, master oscillators and various optical components are described.

First claim

The invention claimed is:

1. A short-pulse, single-pass, amplifier based laser system with a spectrally broadened laser output, the system comprising:
a seed laser; and
a pulse-pumped single-pass laser amplifier configured to emit an amplified, spectrally broadened laser output;
wherein the seed laser is configured to emit a train of ultrafast mid-IR seed pulses;
wherein the laser amplifier is configured to receive and amplify the energy of at least one seed pulse;
wherein the laser amplifier comprises a nonlinear optical medium characterized by a critical power for self focusing, and comprising TM:II-VI polycrystalline material; and
wherein the nonlinear optical medium is irradiated in the single-pass laser amplifier above the critical power for self-focusing, whereby the laser output is spectrally broadened.

2. The laser system as in claim 1 , wherein the nonlinear optical medium has a combination of laser gain and nonlinear optical properties.

3. The system as in claim 1 , further comprising a pulse picker disposed between the seed laser and the laser amplifier, the pulse picker configured to select at least one seed pulse that is synchronized with a pump pulse for amplification.

4. The laser system as in claim 1 , wherein laser gain in the laser amplifier provides amplified pulse power; and wherein the amplified pulse power exceeds the critical power for self-focusing in the nonlinear medium.

5. The laser system as in claim 1 , wherein at least one emitted seed laser pulse has a peak power that exceeds the critical power for self-focusing in the nonlinear medium.

6. The laser system as in claim 1 , wherein the laser output frequency spectrum exceeds one full octave.

7. The laser system as in claim 1 , wherein the laser output wavelength spectral range is 1.8 to 4.5 microns.

8. The system as in claim 1 , further comprising a master oscillator emitting a pulsed fs output to seed the nonlinear optical medium concurrent with the optical pumping of the single-pass laser amplifier.

9. The system as in claim 8 , wherein nonlinear interaction of seed pulses from the master oscillator in the nonlinear optical medium results in spectral broadening of the pulsed output.

10. The system as in claim 1 , further comprising optics for superimposing and focusing pump pulses and seed laser emissions on the nonlinear optical medium.

11. The system as in claim 1 , further comprising optics for separating spectrally broadened output pulses from residual pump pulses.

12. The system as in claim 1 , wherein the peak power of at least one seed pulse exceeds the critical power (P c ) for self-focusing in the nonlinear optical medium.

13. The system as in claim 1 , wherein the nonlinear optical medium is selected from the group consisting of Cr:ZnS, Cr:ZnSe, Cr:CdS, Fe:ZnSe and Fe:ZnS.

14. The system as in claim 1 , wherein the pulsed-pumped single pass amplifier is energized by a pump selected from the group consisting of Er- doped fiber lasers, Tm- doped fiber lasers and TM:II-VI bulk medium lasers.

15. The system as in claim 14 , wherein the pump laser is a mJ, ns, Q-switched bulk Er:YAG laser.

16. The system as in claim 1 , wherein seed laser pulse width is between 1fs and 10 ps.

17. A method of enhancing the properties of a femtosecond laser pulse comprising; propagating a femtosecond seed pulse from a master oscillator into to a TM:II-VI polycrystalline material (GM-NM), wherein the seed pulse is characterized by a pulse energy and a spectral width, wherein the GM-NM is operable to increase peak pulse power and to broaden the spectrum of the seed pulse during in a single pass propagation; and concurrently pumping the GM-NM with an optical pump pulse, wherein the pump pulse energy is sufficient to produce a laser interaction between the seed pulse and the bulk medium, wherein the laser interaction and a least one nonlinear process enhances the properties of the femtosecond seed pulse such that an enhanced pulse with increased pulse energy and increased spectral width is emitted as an output pulse from the GM-NM.

18. The method of claim 17 , wherein the spectrum of output pulses is broader than the spectrum of input pulses from the master oscillator.

19. The method of claim 17 , wherein the temporal pulse width of output pulses is shorter the pulse width of input pulses from the master oscillator.

20. The method of claim 17 , wherein the output energy of pulses is larger than the energy of input pulses from the master oscillator.

21. A short-pulse, single-pass amplifier based laser system for spectral pulse broadening, the system comprising:
a seed laser configured to emit a train of ultrafast mid-IR seed pulses;
a pump laser operable in selectable continuous pumping and pulsed pumping modes;
a single-pass laser amplifier; and
a nonlinear optical medium configured to spectrally broaden and amplify seed pulses in the laser amplifier;
wherein the continuous pumping mode provides high average power amplification of the seed pulse train;
wherein the pulsed pumping mode provides high peak power of the seed pulse train.

22. The system as in claim 21 wherein the nonlinear optical medium provides spectral pulse broadening without pump power.

23. A short-pulse, single-pass, amplifier based laser system with an amplified, spectrally broadened laser output, the system comprising:
a seed laser configured to emit a train of ultrafast mid-IR seed pulses, at least one seed pulse in the pulse train characterized by a central wavelength, a first pulse energy, and a first spectral width;
a pulse-pumped single-pass laser amplifier comprising a bulk medium, which comprises TM:II-VI polycrystalline material, and a pump pulse source, the pump pulse source configured to emit at least one pump pulse that is coincident with the at least one seed pulse, the bulk medium Characterized by a laser gain and at least one non-linear optical property, the laser gain property and the at least one non-linear optical property providing amplification and spectral broadening of the at least one seed pulse, and
a laser output comprising at least one output pulse, the at least one output pulse characterized by a second pulse energy and a second spectral width, wherein the second pulse energy is greater than the first pulse energy and wherein the second spectral width is greater than the first spectral width, whereby the laser output comprises an amplified and spectrally broadened laser output laser output.

24. The system as in claim 23 , wherein the second spectral width spans at least one octave.

25. The system as in claim 23 , wherein the second spectral width is greater than the central wavelength of the at least one seed pulse.

26. The system as in claim 23 , wherein the second spectral width spans at least from 1.8 microns to 4.5 microns.

27. The system as in claim 23 , wherein the laser output further comprises amplified and temporally compressed seed pulses.

28. The system as in claim 23 , wherein the second spectral width is responsive to pump pulse peak power such that an increase in pump pulse peak power corresponds to an increase in the second spectral width.

29. The system as in claim 23 , wherein the nonlinear optical medium is selected from the group consisting of Cr:ZnS, Cr:ZnSe, Cr:CdS, Fe:ZnSe and Fe:ZnS.

Assignees

• Ipg Photonics Corp

Inventors

• Vasilyev Sergey
• Moskalev Igor
• Mirov Michael
• Gapontsev Valentin

Classifications

• H01S3/108

  using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering {(mode locking using a non-linear element H01S3/1112)} · CPC title

• H01S3/1112

  Passive mode locking · CPC title

• H01S3/0057

  Temporal shaping, e.g. pulse compression, frequency chirping (soliton generation and propagation G02F1/3513, H01S3/063 and H01S3/108) · CPC title

• H01S3/094042

  of a fibre laser · CPC title

• H01S3/1685

  Ceramics · CPC title