Laser apparatus having multiple synchronous amplifiers tied to one master oscillator

• US 7,443,903 B2
• Filed: 04/19/2006
• Issued: 10/28/2008
• Est. Priority Date: 04/19/2006
• Status: Active Grant

• Current Assignee: Disco Corporation
• Original Assignee: Mobius Photonics, Inc. (IPG Photonics Corporation)
• Inventors: Leonardo, Manuel J., Byer, Mark W., Smoliar, Laura A.
• Primary Examiner(s): Harvey; Minsun
• Assistant Examiner(s): HAGAN, SEAN P
• Application Number:
  US11/379,276
• Publication Number:
  US 20070248136A1
• Time in Patent Office: 923 Days
• Field of Search: None
• US Class Current: 372/97
• CPC Class Codes: B23K 2101/006 Vehicles
• CPC Class Codes: B23K 26/067 Dividing the beam into multiple beams, e.g. multifocusing
• CPC Class Codes: B23K 26/0673 into independently operating sub-beams, e.g. beam multiplexing to provide laser beams for several stations
• CPC Class Codes: B23K 26/0676 into dependently operating sub-beams, e.g. an array of spots with fixed spatial relationship or for performing simultaneously identical operations
• CPC Class Codes: B23K 26/0884 in at least in three axial directions, e.g. manipulators, robots
• 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 3/2308 Amplifier arrangements, e.g. MOPA
• CPC Class Codes: H01S 3/2316 Cascaded amplifiers
• CPC Class Codes: H01S 3/2383 Parallel arrangements

Abstract

Laser apparatus and methods involving multiple amplified outputs are disclosed. A laser apparatus may include a master oscillator, a beam splitter coupled to the master oscillator, and two or more output heads optically coupled to the beam splitter. The beam splitter divides a signal from the master oscillator into two or more sub-signals. Each output head receives one of the two or more sub-signals. Each output head includes coupling optics optically coupled to the beam splitter. An optical power amplifier is optically coupled between the beam splitter and the coupling optics. Optical outputs from the two or more output heads do not spatially overlap at a target. The master oscillator signal may be pulsed so that optical outputs of the output heads are pulsed and substantially synchronous with each other.

Claims

1. An apparatus, comprising:

a master oscillator;

a beam splitter coupled to the master oscillator, the beam splitter being adapted to divide a beam of light from the master oscillator into two or more sub-signals;

two or more output heads optically coupled in parallel to the beam splitter such that each output head receives one of the two or more sub-signals, wherein each of the two or more output heads includes coupling optics optically coupled to the beam splitter, the coupling optics being configured such that optical outputs from the two or more output heads do not spatially overlap at a target; and

one or more optical power amplifiers optically coupled between the beam splitter and the coupling optics.

2. The apparatus of claim 1 wherein the one or more of the optical power amplifiers are located in the two or more output heads.

3. The apparatus of claim 2 wherein the optical power amplifier includes an amplifier fiber.

4. The apparatus of claim 2 wherein a pump source for the optical power amplifier is located outside the output head and optically coupled to the output head by a multimode optical fiber.

5. The apparatus of claim 2 wherein each of the two or more output heads includes an optical pre-amplifier optically coupled between the beam splitter and the power amplifier.

6. The apparatus of claim 1 wherein the one or more optical power amplifiers includes an amplifier fiber optically coupled between the beam splitter and an output head.

7. The apparatus of claim 1 wherein an effective peak power for the apparatus exceeds a maximum peak power that the amplifier could generate without fiber nonlinearity problems, undesirable distortions, or damage to one or more of the output heads.

8. The apparatus of claim 1 wherein a total output power for the apparatus is greater than about 10 watts.

9. The apparatus of claim 1 wherein the optical power amplifier is a fiber amplifier.

10. The apparatus of claim 1, further comprising an optical pre-amplifier optically coupled between the master oscillator and the one or more power amplifiers.

11. The apparatus of claim 10 wherein the optical pre-amplifier includes two or more optical pre-amplifiers coupled in series.

12. The apparatus of claim 10, wherein the optical pre-amplifier is optically coupled between the master oscillator and the beam splitter, the apparatus further comprising two or more additional optical pre-amplifiers, each additional optical pre-amplifier being optically coupled between the beam splitter and the power amplifiers.

13. The apparatus of claim 12, further comprising one or more additional beam splitters, wherein each additional beam splitter is optically coupled to an output of one of the output optical pre-amplifiers.

14. The apparatus of claim 1 wherein the there are two or more beam splitters and two or more preamplifiers arranged in branching network between the master oscillator and the one or more power amplifiers.

15. The apparatus of claim 1 wherein the master oscillator includes a modulator configured to pulse an optical output of the master oscillator, whereby optical outputs of the two or more output heads are pulsed and substantially synchronous with each other.

16. The apparatus of claim 1, wherein each of the two or more output heads includes an optical wavelength converter optically coupled to wavelength convert an output of the optical power amplifier.

17. The apparatus of claim 16 wherein the output heads are configured to produce output radiation of different vacuum wavelengths.

18. The apparatus of claim 16, wherein optical wavelength converter is a higher harmonic generator, sum frequency generator, difference-frequency generator, optical parametric oscillator, or optical parametric amplifier.

19. The apparatus of claim 16 wherein the optical wavelength converter is a second harmonic generator, a third harmonic generator or a fourth harmonic generator.

20. The apparatus of claim 16 wherein the optical wavelength converter is a third harmonic generator, whereby an optical output of the third harmonic generators is characterized by a vacuum wavelength of about 340 nanometers to about 360 nanometers.

21. The apparatus of claim 16 wherein the optical wavelength converter is a second harmonic generator, whereby an optical output of the second harmonic generators is characterized by a vacuum wavelength of about 520 nanometers to about 540 nanometers.

22. The apparatus of claim 16 wherein a peak power per output head is optimized for non-linear optics and avoiding undesirable nonlinearities.

23. The apparatus of claim 22 wherein a peak power per head is less than a threshold for undesirable nonlinearities and sufficient to provide a wavelength conversion efficiency greater than about 20%.

24. The apparatus of claim 1 wherein the master oscillator includes ytterbium-doped gain medium configured such that the beam of light from the master oscillator is characterized by a vacuum wavelength of about 1.03 to about 1.12 microns.

25. The apparatus of claim 1 wherein the master oscillator comprises a distributed Bragg reflector (DBR) laser, a distributed feedback (DFB) laser, a fiber laser or a narrow band amplified spontaneous emission (ASE) source.

26. The apparatus of claim 1 wherein the master oscillator includes an external modulator.

27. The apparatus of claim 1 wherein the master oscillator produces a master optical signal characterized by a vacuum wavelength between about 500 nm and about 2000 nm.

28. The apparatus of claim 1 wherein the one or more output heads include an optical pulse stretching or pulse compressing mechanism optically coupled to the optical power amplifier.

29. The apparatus of claim 1 wherein the two or more output heads are configured to deliver amplified output radiation in parallel to two or more sides on the target.

30. The apparatus of claim 1 wherein the two or more output heads are configured to synchronously deliver amplified output radiation in parallel to two or more different targets.

31. The apparatus of claim 1 wherein the coupling optics include means to affect the temporal characteristics of the output beam.

32. A method for producing multiple optical outputs, comprising:

generating a master optical signal;

splitting the master optical signal into two or more sub-signals, wherein each sub-signal is directed along a separate optical path;

amplifying each of the two or more sub-signals to produce two or more amplified outputs; and

directing the amplified outputs to a target such that the amplified outputs do not spatially overlap at the target.

33. The method of claim 32, further comprising pre-amplifying the master optical signal before splitting the master optical signal into two or more sub-signals.

34. The method of claim 32, further comprising pre-amplifying each of the two or more sub-signals prior to amplifying each of the two or more sub-signals and after splitting the master optical signal into two or more sub-signals.

35. The method of claim 32, further comprising optically coupling the two or more amplified outputs to different sides on one or more targets.

36. The method of claim 32, further comprising wavelength-converting the two or more amplified outputs to produce two or more wavelength-converted amplified outputs.

37. The method of claim 36 wherein the two or more wavelength-converted outputs includes a third harmonic output.

38. The method of claim 36 wherein the two or more wavelength-converted outputs includes a second harmonic output.

39. The method of claim 36 wherein the two or more amplified outputs are characterized by two or more different vacuum wavelengths.

40. The method of claim 32, further comprising selectively pulse picking the two or more amplified outputs to achieve an arbitrary combination of amplified outputs.

41. The method of claim 32, further comprising stretching or compressing a pulse width of the one or more amplified outputs.

42. The method of claim 32, wherein the target is a metal, ceramic, semiconductor, polymer, composite, thin film, wire, organic material, in vitro or in vivo biological sample, or elementary particles.

43. The method of claim 32 wherein the target comprises a printed circuit (PC) board, an integrated circuit (IC) package, a semiconductor wafer or a semiconductor die, a light emitting diode (LED) wafer, a LED package, LED die or a wire.

44. The method of claim 32 wherein performing material processing of the target comprises performing surface texturing, heat treatment, surface engraving, fine micro-machining, surface ablation, cutting, grooving, bump forming, coating, soldering, brazing, sintering, sealing, stereolithography, maskless lithography, link blowing, wafer scribing, dicing, and marking;

via drilling;

memory repair;

flat panel display repair;

welding, surface diffusion or surface conversion to a compound.

45. The method of claim 32 wherein performing material processing of the target comprises optimizing a pulse repetition frequency and/or pulse width of the amplified outputs for a materials processing application.

46. The method of claim 32 wherein directing the amplified outputs to a target such that the amplified outputs do not spatially overlap at the target includes performing material processing of the target includes synchronously processing multiple targets with the amplified outputs.

47. The method of claim 32, wherein directing the amplified outputs to a target such that the amplified outputs do not spatially overlap at the target comprises performing wafer inspection, medical treatment or laser particle acceleration.

48. An apparatus, comprising:

a master oscillator;

a beam splitter coupled to the master oscillator, the beam splitter being adapted to divide a beam of light from the master oscillator into two or more sub-signals;

two or more output heads optically coupled in parallel to the beam splitter such that each output head receives one of the two or more sub-signals; and

one or more optical power amplifiers optically coupled between the beam splitter and the coupling optics,

wherein the master oscillator includes a modulator configured to pulse an optical output of the master oscillator, whereby optical outputs of the two or more output heads are pulsed and substantially synchronous with each other.