Control of structural modifications in ultrafast laser irradiated glasses on micro and nano-scales

Abstract : Ultrafast lasers are rapidly developing into potential tools for 3D processing of transparent materials, particularly for optical functionalization relying on refractive index engineering. The major advantage derives from strong nonlinear absorption across the bandgap. The subsequent energy localization determines unique photo-physical phenomena followed by thermo-mechanical and structural rearrangements of the dielectric matrix. Challenges are now related to the time-effectiveness of irradiation, correct beam delivery in specific optical designs, and the influence of material properties on the exposure outcomes. Mastering the irradiation result may open new paths for applications involving 3D optical devices. Particularly for light-guiding applications it is suitable to master positive refractive index changes in a time-efficient manner, where the result depends on deposited energy and its relaxation paths. In this respect several irradiation concepts based on adaptive optics in spatial and temporal and polarization domains were developed. We review here some of the applications from various perspectives. A physical aspect is related to time-synchronized energy delivery tuned to the material transient reactions, enabling a synergetic interaction between light and matter and, therefore, optimal results. Examples are given concerning refractive index flip in thermally expansive glasses by thermo-mechanical regulation, energy confinement by nonlinear control. These are accompanied by time-resolved investigations of the refractive index change in conditions of modulated excitation. A second engineering aspect is related to processing efficiency. We give insights into 3D parallel photoinscription techniques and beam-delivery corrections utilizing dynamic wavefront engineering. Additionally, energetic domains of ultrafast laser radiation can generate spontaneous nanoscale material arrangements, leading to form birefringence and modulated index patterns. The associated optical scattering properties are therefore polarization dependent. The laser-induced nanoscale pattern is strongly influenced by the temporal characteristics of the light exposure, with direct effect on the efficiency of the above-mentioned optical properties. Using birefringence and the deriving anisotropic optical properties, polarization sensitive devices were designed and fabricated. The polarization sensitivity allows particular light propagation and confinement properties in 3D structures.
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Communication dans un congrès
International Symposium on Optomechatronic Technologies, Nov 2011, Hong Kong, China
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https://hal-ujm.archives-ouvertes.fr/ujm-00677306
Contributeur : Razvan Stoian <>
Soumis le : mercredi 7 mars 2012 - 21:50:32
Dernière modification le : mercredi 25 juillet 2018 - 14:05:31

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  • HAL Id : ujm-00677306, version 1

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Razvan Stoian. Control of structural modifications in ultrafast laser irradiated glasses on micro and nano-scales. International Symposium on Optomechatronic Technologies, Nov 2011, Hong Kong, China. 〈ujm-00677306〉

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