Quasi-phase-matched parametric chirped pulse amplification systems

• US 6,181,463 B1
• Filed: 03/21/1997
• Issued: 01/30/2001
• Est. Priority Date: 03/21/1997
• Status: Expired due to Term

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Hariharan, Anand, Galvanauskas, Almantas, Harter, Donald J.
• Primary Examiner(s): Moskowitz, Nelson
• Application Number:
  US08/822,967
• Time in Patent Office: 1,411 Days
• Field of Search: 359/330, 359/332, 359/340, 359/345
• US Class Current: 359/330
• CPC Class Codes: A61B 18/22 the beam being directed along or through a flexible conduit, e.g. an optical fibre; Couplings or hand-pieces therefor
• CPC Class Codes: A61C 1/0046 Dental lasers surgical lasers A61B18/20; working by laser beam in general B23K26/00; lasers per se H01S3/00
• CPC Class Codes: B23K 26/0624 using ultrashort pulses, i.e. pulses of 1ns or less
• CPC Class Codes: G02F 1/3548 Quasi phase matching [QPM], e.g. using a periodic domain inverted structure
• CPC Class Codes: G02F 1/39 for parametric generation or amplification of light, infrared or ultraviolet waves
• CPC Class Codes: G02F 1/392 Parametric amplification
• 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 3/0604 in the form of a plate or disc
• CPC Class Codes: H01S 3/115 using intracavity electro-optic devices

Abstract

Use of quasi-phase-matched (QPM) materials for parametric chirped pulse amplification (PCPA) substantially reduces the required pump peak power and pump brightness, allowing exploitation of spatially-multimode and long duration pump pulses. It also removes restrictions on pump wavelength and amplification bandwidth. This allows substantial simplification in pump laser design for a high-energy PCPA system and, consequently, the construction of compact diode-pumped sources of high-energy ultrashort optical pulses. Also, this allows elimination of gain-narrowing and phase-distortion limitations on minimum pulse duration, which typically arise in a chirped pulse amplification system. One example of a compact source of high-energy ultrashort pulses is a multimode-core fiber based PCPA system. Limitations on pulse energy due to the limited core size for single-mode fibers are circumvented by using large multimode core. Limitations on pulse duration and beam quality due to multimode core are circumvented by using a PCPA scheme. Additionally, the large core of the multimode fiber facilitates cladding-pumping by inexpensive and high-power multiple-mode laser diodes.

Claims

1. An optical pulse amplification system, comprising:

a pump source generating optical pump pulses in a first time regime;

a signal source generating optical signal pulses in a second, shorter, time regime;

a stretcher which stretches said optical signal pulses to a duration in said first time regime;

combining elements which receive and combine the optical pump pulses and the stretched optical signal pulses, to thereby provide combined optical pulses which are substantially temporally overlapped; and

a parametric amplifier comprising a quasi-phase-matched crystal receiving the combined optical pulses and amplifying the optical signal pulses using energy of the optical pump pulses; and

a compressor which compresses the amplified optical signal pulses back into said second time regime.

45. The optical pulse amplification system of claim 1, wherein optical signal pulses are of a duration approximately equal to or less than the predetermined duration of the optical pump pulses.

47. The optical pulse amplification system of claim 1, wherein said quasi-phase-matched crystal is periodically poled lithium niobate.

2. An optical pulse amplification system, comprising:

a pump source generating optical pump pulses having a duration of at least 100 ps;

a signal source generating ultrashort optical signal pulses having a duration shorter than that of said pump pulses;

a stretcher which operates to stretch said optical signal pulses so that their durations substantially match that of said pump pulses;

a combiner for combining the optical pump pulses and the stretched optical signal pulses, to provide combined optical pulses which are substantially temporally overlapped;

a parametric amplifier comprising a quasi-phase-matched crystal receiving the combined optical pulses and amplifying the optical signal pulses using energy of the optical pump pulses; and

a compressor which compresses the amplified optical signal pulses to an ultrashort duration shorter than said pump pulses.

3. An optical pulse amplification system, comprising:

a pump source generating optical pump pulses having a duration of at least 100 ps;

a signal source generating chirped optical signal pulses having a time duration substantially similar to that of said pump pulses;

combining elements receiving and combining the optical pump pulses and the optical signal pulses, to thereby provide combined optical pulses which are substantially temporally overlapped;

a parametric amplifier comprising a quasi-phase-matched crystal receiving the combined optical pulses and amplifying the optical signal pulses using energy of the optical pump pulses; and

a compressor which compresses the amplified optical signal pulses to a time duration in the femtosecond regime.

4. An optical pulse amplification system, comprising:

a pump source generating optical pump pulses of a predetermined duration;

a signal source generating optical signal pulses;

combining elements receiving and combining the optical pump pulses and the optical signal pulses, and providing combined optical pulses which are substantially temporally overlapped;

a parametric amplifier comprising a quasi-phase-matched crystal receiving the combined optical pulses and amplifying the optical signal pulses using energy of the optical pump pulses; and

a compressor which compresses the amplified optical signal pulses to a time duration substantially shorter than the predetermined duration of said optical pump pulses.

5. The optical pulse amplification system of claim 4, wherein said pump source comprises at least one pump diode and at least one pulse source.

6. The optical pulse amplification system of claim 5, wherein said pulse source comprises a fiber amplifier.

7. The optical pulse amplification system of claim 4, wherein said signal source comprises:

a signal pulse generator; and

a stretcher receiving and stretching signal pulses generated by the signal pulse generator to a duration approximating said predetermined duration.

8. The optical pulse amplification system of claim 4, wherein said parametric amplifier comprises a multi-stage amplification arrangement having at least two quasi-phase-matched non-linear crystals.

9. The optical pulse amplification system of claim 8, wherein said pump source comprises a Q-switched pulse source.

10. The optical pulse amplification system of claim 9, wherein said signal source comprises a tunable laser diode.

11. The optical pulse amplification system of claim 4 or 9, wherein a pulsewidth of the optical pump pulses is in the range from 200 picoseconds to 5 nanoseconds.

12. The optical pulse amplification system of claim 9, said combining elements including triggering electronics which synchronize the arrival of the optical pump pulses and the optical signal pulses at said parametric amplifier.

13. The optical pulse amplification system of claim 12, wherein said triggering electronics trigger said Q-switched pulse source from signals received from said signal source.

14. The optical pulse amplification system of claim 13, wherein said Q-switched pulse source is an actively Q-switched pulse source, and said signal source is a mode-locked signal source.

15. The optical pulse amplification system of claim 12, wherein said triggering electronics trigger said signal source from signals received from said Q-switched pulse source.

16. The optical pulse amplification system of claim 15, wherein said Q-switched pulse source is a passively Q-switched pulse source, and said signal source is an externally synchronizable laser.

17. The optical pulse amplification system of claim 4, wherein said quasi-phase-matched crystal is a periodically poled nonlinear crystal.

33. The optical pulse amplification system of claim 4, wherein said combining elements includes triggering means for synchronizing the arrival of the pump pulses and the signal pulses at said at said parametric amplifier.

34. The optical pulse amplification system of claim 33, wherein said triggering means triggers said pulse source from signals received from said signal source.

35. The optical pulse amplification system of claim 34, wherein said Q-switched pulse source is an actively pulse source, and said signal source is a mode-locked signal source.

36. The optical pulse amplification system of claim 33, wherein said triggering means triggers said signal source from signals received from said pulse source.

37. The optical pulse amplification system of claim 36, wherein said Q-switched pulse source is a passively Q-switched pulse source, and said signal source is a tunable laser diode.

38. The parametric chirped pulse amplification system of claim 37, wherein said triggering means comprises:

a photodiode detecting the pump pulses of the passively Q-switched pulse source and generating a triggering signal;

tunable diode control means responsive to the triggering signal to control the tunable laser diode.

39. The parametric chirped pulse amplification system of claim 38, further comprising a delay line interposed between the pump source and the parametric amplifier.

46. The optical pulse amplification system of claim 15, wherein said Q-switched pulse source is a passively Q-switched pulse source, and said signal source is a tunable laser diode.

49. The parametric chirped pulse amplification system of claim 33, wherein said triggering means comprises:

a photodiode detecting one of signal pulses from said signal source and pump pulses from said pump source, and generating a triggering signal directed to the other of said signal source and said pump source.

50. The parametric chirped pulse amplification system of claim 35, wherein said triggering means comprises:

a photodiode detecting signal pulses from said mode-locked source, and generating a triggering signal directed to the actively Q-switched pulse source.

18. A parametric chirped pulse amplification system comprising:

a. a pump source generating amplified pump pulses, comprising;

a seed pulse generator;

a pump diode generating pump energy;

a fiber amplifier receiving the seed pulses and

the pump energy and generating the amplified pump pulses;

b. a signal source generating signal pulses;

c. combining means receiving and combining the amplified pump pulses and the signal pulses to thereby produce combined pulses which are temporally overlapped for a substantial portion of said predetermined duration; and

d. a parametric amplifier comprising at least one quasi-phase-matched crystal receiving the combined pulses and amplifying the signal pulses using energy of the amplified pump pulses.

19. The parametric chirped pulse amplification system of claim 18, further comprising a compressor receiving and compressing the signal pulses as amplified by the parametric amplifier.

20. The parametric chirped pulse amplification system of claim 18, wherein said pump source further comprises:

at least one additional pump diode pumping at least one additional fiber amplifier connected in series with the fiber amplifier; and

an acousto-optic modulator interposed between the serial fiber amplifiers.

21. The parametric chirped pulse amplification system of claim 20, wherein said fiber amplifier is a single mode fiber amplifier and said additional fiber amplifier is a multimode fiber amplifier.

22. The parametric chirped pulse amplification system of claim 18, wherein said pump source is configured as a multi-pass arrangement wherein input and output of the fiber amplifier are controlled by an acousto-optic modulator.

23. The parametric chirped pulse amplification system of claim 22, further comprising an additional pump source configured as a multi-pass arrangement and having an additional fiber amplifier controlled by an additional acousto-optic modulator.

24. The parametric chirped pulse amplification system of claim 18, wherein said fiber amplifier is a linear amplifier and is connected to a multi-pass amplifier, and wherein said multi-pass amplifier comprises:

a loop fiber amplifier

a pump connected to the loop fiber amplifier

an acousto-optic modulator controlling input and output of the loop fiber amplifier.

25. The parametric chirped pulse amplification system of claim 18, wherein the pump source generates pump energy having a shorter wavelength than the wavelength of the signal pulses.

26. The parametric chirped pulse amplification system of claim 18, wherein said pump source further comprises a frequency doubler receiving and doubling the frequency of the amplified pump pulses.

27. The parametric chirped pulse amplification system of claim 18, wherein said parametric amplifier is configured as a double stage amplifier comprising a first and a second quasi-phase-matched crystal, and wherein said pump source further comprises a polarized beam splitter splitting the output of the pump source into a first and a second pump channel feeding the first and second quasi-phase-matched crystal, respectively.

28. The parametric chirped pulse amplification system of claim 18, wherein said quasi-phase-matched crystal is a periodically poled nonlinear crystal.

29. A parametric chirped pulse amplification system, comprising:

a. a pump source generating amplified pump pulses, comprising

a seed diode;

a pump laser;

an amplifier responsive to the seed diode and the pump laser to generate pump pulses;

b. a signal source generating signal pulses;

c. combining means receiving and combining the pump pulses and the signal pulses to thereby produce combined and temporally aligned pulses; and

d. a parametric amplifier comprising at least one quasi-phased-matched crystal receiving the combined and temporally aligned pulses and amplifying the signal pulses using energy of the pump pulses.

30. The parametric chirped pulse amplification system of claim 29, further comprising a compressor receiving and compressing the signal pulses as amplified by the parametric amplifier.

31. The parametric chirped pulse amplification system of claim 29, wherein said quasi-phase-matched crystal is a periodically poled nonlinear crystal.

40. The optical pulse amplification system of claim 31, wherein a pulsewidth of the optical pump pulses is in range from 200 picoseconds to 5 nanoseconds.

32. A parametric chirped pulse amplification system, comprising:

a. a pump source generating pump pulses, said pump source comprising pump diodes;

b. a signal source generating signal pulses;

c. combining means receiving and combining the pump and signal pulses to thereby generate combined pulses which are temporally overlapped for a substantial portion of said predetermined duration; and

d. a parametric amplifier receiving the combined pulses and amplifying the signal pulses using energy of the pump pulses.

48. The optical pulse amplification system of claim 32, further comprising a solid state amplifier for amplifying said Q-switched pulses.

41. A parametric chirped pulse amplification system comprising:

a fiber based pump source generating pump pulses;

a signal source generating signal pulses;

a polarized beam splitter splitting the pump pulses into first and a second pump channels;

a first combiner receiving and combining the signal pulses and the pump pulses from the first pump channel, to thereby provide first combined and temporally aligned pulses;

a first parametric amplifier comprising a first quasi-phase-matched crystal receiving the first combined pulses and amplifying the signal pulses using energy of the pump pulses from the first pump channel;

a second combiner receiving and combining the pump pulses from the second pump channel and the signal pulses after being amplified by the first parametric amplifier, to thereby provide second combined and temporally aligned pulses;

a second parametric amplifier comprising a second quasi-phase-matched crystal receiving the second combined pulses and further amplifying the signal pulses using energy of the pump pulses from the second pump channel.

42. The parametric chirped pulse amplification system of claim 41, wherein the pump source comprises a plurality of fiber amplifiers connected in series, and at least one acousto-optic modulator.

43. The parametric chirped pulse amplification system of claim 41, wherein said pump source comprises at least one multi-pass fiber amplifier connected to a pump and controlled by an acousto-optic modulator.

44. The parametric chirped pulse amplification system of claim 41, wherein said quasi-phase-matched crystal is a periodically poled nonlinear crystal.