Dr. Pierre Grua Profile

Dr. Pierre Grua

at Commissariat à l'Énergie Atomique

SPIE Involvement:

Author

Publications (11)

Proceedings Article | 6 December 2016 Open Access

Investigation of mechanisms leading to laser damage morphology

L. Lamaignère, M. Chambonneau, R. Diaz, P. Grua, R. Courchinoux, J.-Y. Natoli, J. L. Rullier

Proceedings Volume 10014, 1001413 (2016) https://doi.org/10.1117/12.2244827

KEYWORDS: Silica, Plasma, Laser ablation, Laser induced damage, Modulation, Ionization, Spatial light modulators, Pulsed laser operation, Absorption, Tellurium

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The original damage ring pattern at the exit surface of fused silica induced by highly modulated nanosecond infrared laser pulses demonstrates the time dependence of damage morphology. Such a damage structure is used to study the dynamics of the plasma issued from open cracks. This pattern originates from electron avalanche in this plasma, which simultaneously leads to an ionization front displacement in air and a silica ablation process. Experiments have shown that the propagation speed of the detonation wave reaches about 20 km/s and scales as the cube root of the laser intensity, in good agreement with theoretical hydrodynamics modeling. During this presentation, we present the different phases and the associated mechanisms leading to this peculiar morphology: • During an incubation phase, a precursor defect provides energy deposit that drives the near surface material into a plasma state. • Next the silica plasma provides free electrons in the surrounding air, under laser irradiation an electron avalanche is initiated and generates a breakdown wave. • Then this breakdown wave leads to an expansion of the air plasma. This latter is able to heat strongly the silica surface as well as generate free electrons in its conduction band. Hence, the silica becomes activated along the breakdown wave. • When the silica has become absorbent, an ablation mechanism of silica occurs, simultaneously with the air plasma expansion, resulting in the formation of the ring patterns in the case of these modulated laser pulses. These mechanisms are supported by experiments realized in vacuum environment. A model describing the expansion of the heated area by thermal conduction due to plasma free electrons is then presented. Next, the paper deals with the two damage formation phases that are distinguished. The first phase corresponds to the incubation of the laser flux by a subsurface defect until the damage occurrence: an incubation fluence corresponds to this phase. The second is related to the damage expansion that only refers to the energy deposit feeding the activation mechanism up to the end of the pulse: an expansion fluence corresponds to this phase. A striking feature is that the damage diameters are proportional to the fluence of expansion at a given shot fluence. Indirectly, the fluences of incubation by the precursors are then determined.

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Proceedings Article | 23 November 2015 Paper

Study of laser-induced damage at 1064nm in fused silica samples in vacuum environment

R. Diaz, M. Chambonneau, P. Grua, J.-L. Rullier, J.-Y. Natoli, L. Lamaignère

Proceedings Volume 9632, 96320F (2015) https://doi.org/10.1117/12.2195471

KEYWORDS: Laser induced damage, Silica, Plasma, Laser ablation, Ionization, Electrons, Spatial light modulators, Absorption, Chronology, Pulsed laser operation

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Proceedings Article | 31 October 2014 Paper

Laser-induced damage morphology in fused silica at 1064 nm in the nanosecond regime

Maxime Chambonneau, Romain Diaz, Guillaume Duchateau, Pierre Grua, Jean-Yves Natoli, Jean-Luc Rullier, Laurent Lamaignère

Proceedings Volume 9237, 923715 (2014) https://doi.org/10.1117/12.2068733

KEYWORDS: Silica, Laser induced damage, Spatial light modulators, Plasma, Electrons, Ionization, Laser ablation, Wave propagation, Pulsed laser operation, Photomicroscopy

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Proceedings Article | 22 September 2014 Paper

Measurements of laser induced damage density produced with multiple longitudinal mode pulses in fused silica

R. Diaz, M. Chambonneau, P. Grua, J.-L. Rullier, J.-Y. Natoli, L. Lamaignère

Proceedings Volume 9238, 923803 (2014) https://doi.org/10.1117/12.2073234

KEYWORDS: Spatial light modulators, Absorption, Laser induced damage, Silica, Annealing, Photomicroscopy, Resistance, Eye models, Atmospheric plasma, Plasma

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Proceedings Article | 28 November 2011 Paper

Luminescence of different surface flaws in high purity silica glass under UV excitation

J. Fournier, J. Néauport, P. Grua, V. Jubera, E. Fargin, D. Talaga, S. Jouannigot

Proceedings Volume 8190, 819021 (2011) https://doi.org/10.1117/12.899177

KEYWORDS: Luminescence, Laser induced damage, Silica, Temperature metrology, Ultraviolet radiation, Germanium, Glasses, Oxygen, Polishing, Solar thermal energy

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Proceedings Article | 30 December 2008 Paper

H. Bercegol, P. Grua

Proceedings Volume 7132, 71321B (2008) https://doi.org/10.1117/12.804419

KEYWORDS: Silica, Laser induced damage, Absorption, Electrons, Spherical lenses, Plasma, Laser energy, Dielectrics, Mechanics, Laser damage threshold

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Proceedings Article | 18 December 2007 Paper

Progress in the understanding of fracture related laser damage of fused silica

H. Bercegol, P. Grua, D. Hébert, J-P. Morreeuw

Proceedings Volume 6720, 672003 (2007) https://doi.org/10.1117/12.752830

KEYWORDS: Silica, Laser induced damage, Absorption, Dielectrics, Laser energy, Temperature metrology, Polarization, Electromagnetism, Polishing, Surface finishing

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