Hollow-core photonic crystal fiber based optical component for broadband radiation generation

Patent metadata

Field	Value
Publication number	US-11699889-B2
Application number	US-202017621723-A
Country	US
Kind code	B2
Filing date	Jun 3, 2020
Priority date	Jun 25, 2019
Publication date	Jul 11, 2023
Grant date	Jul 11, 2023

Abstract

A broadband source device configured for generating broadband radiation or white light output. The broadband source device includes a gas cell, and a hollow-core photonic crystal fiber at least partially enclosed within the gas cell. A gas mixture is within the gas cell and the hollow-core photonic crystal fiber. The gas mixture includes at least one Raman active molecular gas constituting more than 2% of the gas mixture, such that the broadband source device operates in a balanced Kerr-Raman nonlinear interaction regime.

First claim

The invention claimed is:

1. A broadband radiation source device, configured for generating a broadband output, the device comprising:
an optical component, comprising:
a gas cell, and
a hollow-core photonic crystal fiber at least partially enclosed within the gas cell; and

a gas mixture within the gas cell and the hollow-core photonic crystal fiber, the gas mixture comprising at least one Raman active molecular gas constituting more than 2% of the gas mixture,
wherein the broadband radiation source device is configured to operate in a balanced Kerr-Raman nonlinear interaction regime and output an output spectrum of the output radiation that is flat and/or smooth over a range of wavelengths.

2. The device as claimed in claim 1 , wherein the at least one Raman active molecular gas constitutes at least 5% of the gas mixture.

3. The device as claimed in claim 1 , wherein the at least one Raman active molecular gas constitutes at least 10% of the gas mixture.

4. The device as claimed in claim 1 , wherein the balanced Kerr-Raman nonlinear interaction regime is defined by complementary processes comprising a Raman process and a Kerr-based modulational instability process, such that the output spectrum of the broadband radiation source device exhibits a spectral broadening.

5. The device as claimed in claim 1 , further comprising a pump laser for outputting a plurality of pump pulses.

6. The device as claimed in claim 1 , wherein the gas mixture comprises at least one noble gas and the at least one Raman active molecular gas.

7. The device as claimed in claim 1 , wherein the gas mixture comprises a mixture of at least two Raman active molecular gases.

8. The as claimed in claim 1 , wherein the hollow-core photonic crystal fiber is wholly comprised within the gas cell.

9. The device as claimed in claim 1 , wherein the gas cell comprises a plurality of sub-cells, the plurality of sub-cells comprising at least two end sub-cells, enclosing respective ends of the hollow-core photonic crystal fiber.

10. The device as claimed in claim 1 , wherein the at least one Raman active molecular gas constitutes between 10% and 30% of the gas mixture.

11. The device as claimed in claim 1 , further comprising an optical diagnostic device configured to measure the output radiation, output from the optical component.

12. The device as claimed in claim 11 , comprising a processor configured to evaluate the measured output radiation so as to determine whether the broadband radiation source device is operating in the balanced Kerr-Raman nonlinear interaction regime.

13. The device as claimed in claim 1 , wherein the broadband output comprises a wavelength range of 200 nm to 2000 nm, or a sub-range within this range.

14. A metrology device comprising the device as claimed in claim 1 .

15. A method for generating broadband radiation using a broadband radiation source device comprising: an optical component comprising a gas cell, a hollow-core photonic crystal fiber at least partially enclosed within the gas cell; and a gas mixture comprising at least one Raman active molecular gas within the gas cell and the hollow-core photonic crystal fiber and using a pump laser in optical connection with the gas-filled hollow-core photonic crystal fiber, the method comprising:
measuring output radiation, output from the optical component; and
evaluating the measured output radiation so as to determine whether the broadband radiation source device is operating in a balanced Kerr-Raman nonlinear interaction regime, wherein the evaluating comprises evaluating whether an output spectrum of the output radiation is flat and/or smooth over a range of wavelengths.

16. The method according to claim 15 , wherein the evaluating comprises determining whether a flatness of a spectral profile of the output spectrum is better than 10 dB in a desired wavelength range.

17. The method according to claim 15 , further comprising optimizing one or more values of one or more operating parameters relating to generation of the broadband radiation, so as to ensure operation in the balanced Kerr-Raman nonlinear interaction regime.

18. The method according to claim 15 , wherein the gas mixture comprises at least one Raman active molecular gas constituting more than 2% of the gas mixture.

19. The method according to claim 15 , wherein the balanced Kerr-Raman nonlinear interaction regime is defined by complementary processes comprising a Raman process and a Kerr-based modulational instability process, such that the output spectrum of the broadband radiation source device exhibits a spectral broadening.

Assignees

• Asml Netherlands Bv
• Asme Netherlands B V

Inventors

• Abdolvand Amir

Classifications

• H01S3/06704 Primary

  Housings; Packages · CPC title

• G02F1/365

  in an optical waveguide structure (G02F1/377, {G02F1/395} take precedence) · CPC title

• H01S3/06741

  Photonic crystal fibre, i.e. the fibre having a photonic bandgap · CPC title

• H01S3/094038

  End pumping · CPC title

• H01S3/305

  in a gas · CPC title