Abstract

A Petawatt facility called PETAL (PETawatt Aquitaine Laser) is under development near the LMJ (Laser MegaJoule) at CEA Cesta, France. PETAL facility uses chirped pulse amplification (CPA) technique. This system needs large pulse compression gratings exhibiting damage threshold of more than 4 J/cm<sup>2</sup> in normal beam at 1.053&mu;m and for 500fs pulses. In this paper, we present our recent progress and developments of such pulse compression gratings. We have shown in previous works that the enhancement of the near electric field inside the pillars of the grating drives the damage threshold. This was evidenced from a macroscopic point of view by laser damage testing. We herein demonstrate that damage morphology during damage initiation at the scale of the grating groove is also consistent with this electric field dependence. Some recent grating designs will also be detailed.

Highlights

  • We have shown in previous works that damage threshold is driven by the enhancement of the near electric field inside the pillars of the grating

  • The PETAL facility [1] laser beam, currently under construction on the Megajoule Laser (LMJ), in France [2] consists in the combination of a high intensity multi-Petawatt laser line synchronized with the nanosecond LMJ laser beams

  • A multilayer dielectric (MLD) grating consists of a multidielectric mirror with a grating engraved in its top layer leading to a significant improvement in the laser induced damage (LID) threshold thanks to the suppression of metal in the structure [7]

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Summary

Introduction

The PETAL facility [1] laser beam, currently under construction on the Megajoule Laser (LMJ), in France [2] consists in the combination of a high intensity multi-Petawatt laser line synchronized with the nanosecond LMJ laser beams. This system needs large pulse compression gratings that request damage threshold better than 4 J/cm2 in normal beam at 1.053 m for 500 fs pulses. We have shown in previous works that damage threshold is driven by the enhancement of the near electric field inside the pillars of the grating.

Results
Conclusion

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