System and method for pumping laser sustained plasma with a frequency converted illumination source

Patent metadata

Field	Value
Publication number	US-10568195-B2
Application number	US-201816051559-A
Country	US
Kind code	B2
Filing date	Aug 1, 2018
Priority date	May 30, 2018
Publication date	Feb 18, 2020
Grant date	Feb 18, 2020

Abstract

A system for generating pump illumination for laser sustained plasma (LSP) is disclosed. In embodiments, the system includes an illumination source configured to output illumination having a first spectral frequency and an optical frequency converter. The optical frequency converter can be configured to receive the illumination having the first spectral frequency from the illumination source and configured to output pump illumination having a second spectral frequency that is different from the first spectral frequency.

First claim

What is claimed:

1. A system for generating pump illumination for a laser sustained plasma, comprising:
an illumination source configured to output illumination having a first spectral frequency, wherein a wavelength of the illumination having the first spectral frequency is in the range of 100 nanometers (nm) to 100 micrometers (μm); and
an optical frequency converter configured to receive the illumination having the first spectral frequency from the illumination source and configured to output pump illumination having a second spectral frequency that is different from the first spectral frequency.

2. The system of claim 1 , further comprising one or more optical elements configured to direct the pump illumination to the laser sustained plasma.

3. The system of claim 1 , wherein the illumination source comprises a continuous wave illumination source.

4. The system of claim 3 , wherein the optical frequency converter comprises an optical resonator.

5. The system of claim 4 , wherein the optical resonator comprises an optical cavity.

6. The system of claim 1 , wherein the illumination source comprises a pulsed illumination source.

7. The system of claim 6 , wherein a repetition rate of the pulsed illumination source is higher than an inverse time of plasma decay for the laser sustained plasma.

8. The system of claim 6 , wherein a repetition rate of the pulsed illumination source is at least 200 kilohertz.

9. The system of claim 6 , wherein a repetition rate of the pulsed illumination source is in the range of 1 megahertz to 1000 megahertz.

10. The system of claim 6 , wherein a pulse duration of the pulsed illumination source is in the range of 1 picosecond to 1000 picoseconds.

11. The system of claim 1 , wherein the optical frequency converter comprises an optical frequency multiplier.

12. The system of claim 11 , wherein the optical frequency multiplier is configured to double, triple, or quadruple the spectral frequency of the illumination received from the illumination source.

13. The system of claim 1 , wherein the illumination source comprises a Nd:YAG laser.

14. The system of claim 1 , wherein the illumination source comprises at least one of a Yt fiber laser or a Yt disk laser.

15. The system of claim 1 , further comprising a housing configured to contain the illumination source and the optical frequency converter.

16. The system of claim 1 , wherein the first spectral frequency is in the range of 3 terahertz (THz) to 3 petahertz (PHz).

17. A system for generating broadband illumination, comprising:
a plasma forming material;
an illumination source configured to output illumination having a first spectral frequency, wherein a wavelength of the illumination having the first spectral frequency is in the range of 100 nanometers (nm) to 100 micrometers (μm);
an optical frequency converter configured to receive the illumination having the first spectral frequency from the illumination source and configured to output pump illumination having a second spectral frequency that is different from the first spectral frequency;
one or more optical elements configured to direct the pump illumination to the plasma forming material, whereby the pump illumination causes the plasma forming material to form a laser sustained plasma that emits broadband illumination.

18. The system of claim 17 , further comprising one or more collection optics configured to receive the broadband illumination and direct the broadband illumination to an output.

19. The system of claim 17 , wherein the illumination source comprises a continuous wave illumination source.

20. The system of claim 19 , wherein the optical frequency converter comprises an optical resonator.

21. The system of claim 20 , wherein the optical resonator comprises an optical cavity.

22. The system of claim 17 , wherein the illumination source comprises a pulsed illumination source.

23. The system of claim 22 , wherein a repetition rate of the pulsed illumination source is higher than an inverse time of plasma decay for the laser sustained plasma.

24. The system of claim 22 , wherein a repetition rate of the pulsed illumination source is at least 200 kilohertz.

25. The system of claim 22 , wherein a repetition rate of the pulsed illumination source is in the range of 1 megahertz to 1000 megahertz.

26. The system of claim 22 , wherein a pulse duration of the pulsed illumination source is in the range of 1 picosecond to 1000 picoseconds.

27. The system of claim 17 , wherein the optical frequency converter comprises an optical frequency multiplier.

28. The system of claim 27 , wherein the optical frequency multiplier is configured to double, triple, or quadruple the spectral frequency of the illumination received from the illumination source.

29. The system of claim 17 , wherein the illumination source comprises a Nd:YAG laser.

30. The system of claim 17 , wherein the illumination source comprises at least one of a Yt fiber laser or a Yt disk laser.

31. The system of claim 17 , further comprising a housing configured to contain the illumination source and the optical frequency converter.

32. The system of claim 17 , wherein the first spectral frequency is in the range of 3 terahertz (THz) to 3 petahertz (PHz).

33. A method of generating broadband illumination, comprising:
generating illumination having a first spectral frequency, wherein a wavelength of the illumination having the first spectral frequency is in the range of 100 nanometers (nm) to 100 micrometers (μm);
converting the illumination having the first spectral frequency to pump illumination having a second spectral frequency that is different from the first spectral frequency;
directing the pump illumination to a plasma forming material, whereby the pump illumination causes the plasma forming material to form a laser sustained plasma that emits broadband illumination.

34. A system for generating pump illumination for a laser sustained plasma, comprising:
a pulsed illumination source configured to output illumination having a first spectral frequency, wherein a repetition rate of the pulsed illumination source is higher than an inverse time of plasma decay for the laser sustained plasma; and
an optical frequency converter configured to receive the illumination having the first spectral frequency from the pulsed illumination source and configured to output pump illumination having a second spectral frequency that is different from the first spectral frequency.

35. A system for generating broadband illumination, comprising:
a plasma forming material;
a pulsed illumination source configured to output illumination having a first spectral frequency;
an optical frequency converter configured to receive the illumination having the first spectral frequency from the pulsed illumination source and configured to output pump illumination having a second spectral frequency that is different from the first spectral frequency;
one or more optical elements configured to direct the pump illumination to the plasma forming material, whereby the pump illumination causes the plasma forming material to form a laser sustained plasma that emits broadband illumination, wherein a repetition rate of the pulsed illumination source is high

Assignees

• Kla Tencor Corp

Inventors

• Bezel Ilya
• Shchemelinin Anatoly
• Derstine Matthew

Classifications

• H01S3/0092

  Nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity (nonlinear frequency conversion per se G02F1/35) · CPC title

• G02F1/37

  for second-harmonic generation {(G02F1/3532 takes precedence)} · CPC title

• G02F1/353 Primary

  Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams · CPC title

• H01S3/06708

  Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering (optical fibres as passive waveguides G02B6/02) · CPC title

• H01S3/162

  transition metal · CPC title