Diffraction gratings for pulse compression applications

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The Clarte team takes benefit of its strong background on diffraction grating theory to develop pulse compression gratings in close collaboration with CEA for the PETAL project, and LOA, LULI for the Apollon project.

Optimization of the profile to minimize the light enhancement and increase the LIDT
In close collaboration with CEA CESTA, we proposed to minimize the light enhancement inside the pillar of the grating and we demonstrated an increase of the laser induced damage threshold [1].

The company Horiba Jobin Yvon fabricated diffraction gratings exhibiting laser induced damaged threshold higher than 4.5 J/cm2 in right section.

More recently, we demontrasted that damages initiate at the opposite to incoming wave with good concordance with E field computations. SEM measurements showed that ripples reduce damage threshold of MLD gratings [3].

[1] N. Bonod, J. Néauport, “Optical performances and laser induced damage threshold improvement of diffraction gratings used as compressors in high power lasers,” Opt. Commun. 260, 649-655 (2006)
[2] J. Neauport, E. Lavastre, G. Razé, G. Dupuy, N. Bonod, M. Balas, G. de Villele, J. Flamand, S. Kaladgew, F. Desserouer, “Effect of electric field on laser induced damage threshold of multilayer dielectric gratings,” Opt. Express 15, 12508-12522 (2007).
[3] S. Hocquet, J. Néauport, N. Bonod, “The role of electric field polarization of the incident laser beam in the short pulse damage mechanism of pulse compression gratings,” Appl. Phys. Lett. 99, 061101 (2011)

Hybrid metallo-dielectric gratings

High number of dielectric layers + large area : stress inside the multilayer stack that can lead to crazings.Idea proposed in 2006 : ‘A metal layer is inserted between the substrate and the dielectric stack to reduce the number of dielectric bilayers and thus the mechanical stress within the stack’ N. Bonod et al., Opt. Commun. 260, 649-655 (2006)

Hybrid metal-dielectric gratings were fabricated by Horiba Jobin Yvon and reflected efficiencies in the -1st order higher than 96% were reported, together with LIDT higher than 3J/cm2 [4].

[4] J. Neauport, N. Bonod, S. Hocquet, S. Palmier, G. Dupuy, “Mixed metal dielectric gratings for pulse compression,” Opt. Express 18, 23776-23783 (2010)

Patents :

3. “Réseau de diffraction multicouches à mixture de diélectriques,” demande de dépôt de brevet à l’INPI 21/02/2011, N°1251570. Propriétaires : CEA, CNRS, Inventeurs : N. Bonod, L. Gallais, E. Lavastre, J. Néauport.
2. “Réseau de diffraction réfléchissant optimisé,” demande de dépôt de brevet à l’INPI le 17/12/2009, N°09 59 157. Propriétaires : CNRS, Ecole Polytechnique, Inventeurs : Nicolas Bonod, Jean-Paul Chambaret. Demande d’extension PCT N° PCT/FR2010/052684 déposée le 13/12/2010.
1. Dispositif optique dispersif à cristal photonique tridimensionnel, Brevet Numéro 0757815. Date de publication : 25/09/2007. Propriétaires : CEA, CNRS, Inventeurs : J. Neauport, N. Bonod. Extension à l’international PCT/EP2008/062708. demandée le 14/04/2009.