Linear time-gate method and system for ultrashort pulse characterization

Patent metadata

Field	Value
Publication number	US-11415461-B2
Application number	US-201816650828-A
Country	US
Kind code	B2
Filing date	Sep 24, 2018
Priority date	Sep 25, 2017
Publication date	Aug 16, 2022
Grant date	Aug 16, 2022

Abstract

A method comprising forming a linear temporal non-stationary amplitude filter by interacting a high intensity ultrashort laser pump pulse with a photo-excitable material, focusing an ultrashort broadband laser probe pulse over the photo-excited material, acquiring a two-dimensional spectrogram and retrieving amplitudes and phases of both temporal probe pulse and linear non-stationary amplitude filter from the two-dimensional spectrogram.

First claim

The invention claimed is:

1. A method, comprising forming a linear temporal non-stationary amplitude filter by interacting a high intensity ultrashort laser pump pulse with a photo-excitable material, focusing an ultrashort broadband laser probe pulse over the photo-excited material, acquiring a two-dimensional spectrogram in which both temporal probe pulse and the linear non-stationary amplitude filter are encoded, and retrieving amplitudes and phases of both the temporal probe pulse and the linear non-stationary amplitude filter from the two-dimensional spectrogram, wherein the method comprises convoluting the probe pulse with the photo-excited material by varying a delay between the probe pulse and the photo-excited material forming the linear temporal non-stationary amplitude filter in scanning delay steps, frequency resolving and measuring a resulting convolution signal for a range of delay positions, recording the non-stationary amplitude filter and the probe pulse from the convolution signal, and retrieving amplitudes and phases of the non-stationary amplitude filter and the probe pulse from the recorded non-stationary amplitude filter and the probe pulse, yielding temporal characterization of the ultrashort broadband probe pulse.

2. The method of claim 1 , comprising varying the delay-using a translation stage on the path of the probe pulse and acquiring a spectrum for a range of delay values.

3. The method of claim 1 , wherein said-varying the delay introducing a variable delay along one dimension of the pump pulse.

4. The method of claim 1 , comprising introducing a variable delay along one dimension of the pump pulse, focusing the pump and probe pulses to a line along the one dimension, and then dispersing the probe pulse, each point of the line in the one dimension being dispersed corresponding to a spectrum at different pump delays.

5. The method of claim 1 , comprising introducing spectral interferometry on the probe pulse path.

6. The method of claim 1 , comprising one of: i) transmitting the probe pulse through the excited material and ii) reflecting the probe pulse from a surface of the excited material; and collecting the probe pulse after focus.

7. The method of claim 1 , comprising selecting a wavelength of the pump pulse depending on the photo-excitable material.

8. The method of claim 1 , wherein the pump pulse has a duration of at most 1 ps, an intensity of at least 1×10 12 W/cm 2 at the surface of the material and a wavelength in a range between 200 nm and 20 microns; and the probe pulse has a duration comprised in a range between 5 fs and 1 ns, an intensity of at most 1×10 11 W/cm 2 at the surface of the material and a wavelength in a range between 200 nm and 20 microns.

9. The method of claim 1 , comprising adjusting an energy of the pump pulse to reach an absorption saturation of the probe pulse and a fluence below the photo-excitable material ablation threshold.

10. The method of claim 1 , wherein the photo-excitable material is one of: a low band-gap dielectric and a low band-gap semi-conductor.

11. The method of claim 1 , wherein the probe pulse has a duration comprised in a range between 5 fs and 1 ns an intensity of at most 1×10 11 W/cm 2 at the surface of the material and a wavelength in a range between 200 nm and 20 microns.

12. The method of claim 1 , wherein the probe pulse has a duration comprised in a range between 5 fs and 1 ns an intensity of at most 1×10 11 W/cm 2 at the surface of the material, a wavelength in a range between 200 nm and 20 microns, and 0>Δω/ω 0 >2, Δω being a bandwidth thereof and ω 0 a central frequency thereof.

13. The method of claim 1 , wherein the material has a band gap in a range between 0.5 and 9 eV.

14. The method of claim 1 , wherein the material has a band gap in a range between 0.5 and 4 eV.

15. The method of claim 1 , wherein the photo-excitable material has a thickness comprised in a range between 100 nm and 100 μm.

16. The method of claim 1 , wherein the photo-excitable material has a thickness of at most 2 mm.

17. A method, comprising propagating a first ultrashort laser pulse through a linear temporal non-stationary amplitude filter formed by a low band-gap material photoexcited by a second independent ultrashort laser pulse, convoluting the first ultrashort laser pulse with the photo-excited material by varying a delay between the first ultrashort laser pulse and the photo-excited material forming the linear temporal non-stationary amplitude filter, measuring, for a range of delay positions, a resulting spectrum as a function of the delay, and obtaining amplitude and phase characterization of a time-gate induced in the material by the second ultrashort laser pulse and of the first ultrashort laser pulse from the measurement as a function of the delay.

18. The method of claim 17 , wherein the material has a band gap in a range between 0.5 and 9 eV; and the first ultrashort laser pulse has with a duration comprised in a range between 5 fs and 1 ns an intensity of at most 1×10 11 W/cm 2 at a surface of the material.

19. The method of claim 17 , comprising one of: i) transmitting the first ultrashort laser pulse through the photoexcited material and ii) reflecting the first ultrashort laser pulse from a surface of the photoexcited material.

Assignees

• Inst Nat Rech Scient
• Univ Bordeaux
• Centre Nat Rech Scient
• Commissariat Energie Atomique
• Luniversite De Bordeaux
• Commissariat A Lenergie Atomique Et Aux Energies

Inventors

• Lassonde Philippe
• Ernotte Guilmot
• Schmidt Bruno E
• Légaré François
• Petit Stéphane
• Delagnes Jean-Christophe
• Cormier Eric
• Leblanc Adrien

Classifications

• G01J3/42 Primary

  Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry (beam switching arrangements G01J3/08) · CPC title

• G01J3/45

  Interferometric spectrometry · CPC title

• G01J11/00 Primary

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