Method and system for measurement of ultra-high laser intensity

Patent metadata

Field	Value
Publication number	US-11456570-B2
Application number	US-202016925003-A
Country	US
Kind code	B2
Filing date	Jul 9, 2020
Priority date	Jul 11, 2019
Publication date	Sep 27, 2022
Grant date	Sep 27, 2022

Abstract

A method and a system for measurement of high laser field intensity, the method comprising tight focusing a non-Gaussian azimuthally polarized laser mode beam to a focusing spot, measuring a spectral line shape of a selected ionization state induced by a longitudinal oscillating magnetic field created by the tight focusing in the focusing spot; and determining the laser intensity from the spectral line shape. The system comprises a laser source of a peak power in a range between 100 terawatt and 10 petawatt; a converter unit; a tight focusing optics; and spectral measurement means; wherein the converter unit polarizes a main laser beam from the laser source into a non-Gaussian azimuthally polarized laser mode beam; the tight focusing optics focuses the azimuthally polarized laser mode beam to a focusing spot, yielding a longitudinal oscillating magnetic field of an intensity proportional to the laser intensity, the spectral measurement means measuring a line shape of a selected ionization state induced by the longitudinal oscillating magnetic field in focusing spot.

First claim

The invention claimed is:

1. A method for measurement of high laser field intensity, comprising tight focusing a non-Gaussian azimuthally polarized laser mode beam to a focusing spot, measuring a spectral line shape of a selected ionization state induced by a longitudinal oscillating magnetic field created by said tight focusing in the focusing spot; and determining the laser intensity from the spectral line shape.

2. The method of claim 1 , comprising selecting a high peak power laser source; polarizing a main laser beam into an azimuthally polarized TE 01 mode; focusing the azimuthally polarized TE 01 mode in the focusing spot having a size in a range between about 400 nm and about 2 μm with an intensity comprised in a range between about 10 22 W/cm 2 and 10 23 W/cm 2 .

3. The method of claim 1 , comprising selecting a laser source laser source of a peak power in a range between 100 terawatt and 10 petawatt; selecting a high numerical aperture optics; polarizing a main laser beam into an azimuthally polarized TE 01 mode; focusing the azimuthally polarized TE 01 mode in the focusing spot with an intensity comprised in a range between 10 22 W/cm 2 and 10 23 W/cm 2 .

4. The method of claim 1 , wherein the laser intensity is in a range between 10 21 W/cm 2 and 10 23 W/cm 2 and the longitudinal oscillating magnetic field has an intensity in a range between 10kT and 500kT.

5. The method of claim 1 , comprising focusing an auxiliary beam derived from a main laser beam on a thin foil target located at the focal plane of the non-Gaussian azimuthally polarized laser mode beam.

6. The method of claim 1 , comprising focusing an auxiliary beam derived from a main laser beam on a foil target of a thickness in a range between about 10 mm and about 50 mm located at the focal plane of the non-Gaussian azimuthally polarized laser mode beam.

7. The method of claim 1 , comprising focusing an auxiliary beam derived from a main laser beam on a thin foil target located at the focal plane of the non-Gaussian azimuthally polarized laser mode beam, thereby yielding a plasma localized in a thickness in a range between 300 nm and 1 μm from either side of the focal plane of the non-Gaussian azimuthally polarized laser mode beam and of a density less than the critical density n c .

8. The method of claim 1 , comprising focusing an auxiliary beam derived from a main laser beam on a thin foil target located at the focal plane of the non-Gaussian azimuthally polarized laser mode beam, thereby yielding a plasma localized in a thickness in a range between 300 nm and 1 μm from either side of the focal plane of the non-Gaussian azimuthally polarized laser mode beam and of a density in a range between n c /10 and n c , where n c , is the critical density.

9. A system for measurement of high laser field intensity, comprising:
a laser source of a peak power in a range between 100 terawatt and 10 petawatt;
a converter unit;
a tight focusing optics; and
spectral measurement means;
wherein said converter unit polarizes a main laser beam from the laser source into a non-Gaussian azimuthally polarized laser mode beam; said tight focusing optics focuses the azimuthally polarized laser mode beam to a focusing spot, yielding a longitudinal oscillating magnetic field of an intensity proportional to the laser intensity, said spectral measurement means measuring a line shape of a selected ionization state induced by the longitudinal oscillating magnetic field in focusing spot.

10. The system of claim 9 , wherein the azimuthally polarized laser mode beam is a laser pulse of energy in a range between 1J and 1 kJ.

11. The system of claim 9 , wherein the tight focusing optics is a high numerical aperture reflective optics.

12. The system of claim 9 , wherein the tight focusing optics has a numerical aperture in a range between 0.7 and 1.

13. The system of claim 9 , wherein the tight focusing optics is a combination of a parabolic mirror and an ellipsoid plasma mirror of a numerical aperture in a range between 0.7 and 1.

14. The system of claim 9 , wherein the focal point of the tight focusing optics has an intensity comprised in a range between 10 22 W/cm 2 and 10 23 W/cm 2 .

15. The system of claim 9 , wherein the laser intensity is in a range between 10 21 W/cm 2 and 10 23 W/cm 2 .

16. The system of claim 9 , wherein the longitudinal oscillating magnetic field has an intensity in a range between 10kT and 500kT.

17. The system of claim 9 , further comprising auxiliary focusing optics and a thin foil target located at the focal plane of the azimuthally polarized laser mode beam, said auxiliary focusing optics focusing an auxiliary beam derived from the main laser beam, of a pulse in a range between 10fs and 30fs, synchronized with the main laser beam, to the thin foil target.

18. The system of claim 9 , further comprising an auxiliary focusing optics and a foil target located at the focal plane of the azimuthally polarized laser mode beam, said auxiliary focusing optics focusing an auxiliary beam derived from the main laser beam, of a pulse in a range between 10fs and 30fs, synchronized with the main laser beam, to the foil target; wherein the auxiliary focusing optics is an off-axis parabola.

19. The system of claim 9 , further comprising an auxiliary focusing optics and a foil target located at the focal plane of the azimuthally polarized TE 01 mode, said auxiliary focusing optics focusing an auxiliary beam derived from the main laser beam, of a pulse in a range between 10fs and 30fs, synchronized with the main laser beam, to the foil target; wherein the foil target has a thickness in a range between 10 mm and 50 mm.

20. A method for measuring ultra-high laser intensity, comprising generating a longitudinal oscillating magnetic field of an intensity proportional to the laser intensity in a focusing point of highest intensity by tight focusing a non-Gaussian azimuthally polarized laser mode beam, measuring a line shape of a selected ionization state induced by the longitudinal oscillating magnetic field in the focusing spot, and determining the laser intensity from the spectral line shape.

Assignees

• Inst Nat Rech Scient

Inventors

• Kieffer Jean-Claude

Classifications

• H01S3/0014 Primary

  Monitoring arrangements not otherwise provided for (photometry G01J1/00, e.g. G01J1/4257; radiation pyrometry G01J5/00; measuring coherence of light G01J9/00; measuring wavelength of light G01J9/00, e.g. G01J9/0246; measuring optical pulses G01J11/00; calorimetrically measuring power of laser beams G01K17/003) · CPC title

• G01J11/00

  Measuring the characteristics of individual optical pulses or of optical pulse trains · CPC title

• H01S2301/20

  Lasers with a special output beam profile or cross-section, e.g. non-Gaussian · CPC title

• H01S3/005

  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 title

• G01N21/55

  Specular reflectivity · CPC title