Nanostructuring of linear and non-linear properties of a photosensitive glass by femtosecond laser

Dans le cadre de cette thèse un verre phosphate de zinc dopé avec des cations d’argent a été irradié par laser femtoseconde. Cette irradiation induit l’apparition dans le voxel de focalisation, d’une émission de fluorescence et une génération de second harmonique au sein du verre. La fluorescence a été attribuée à la création d’agrégats fluorescents composé d’une dizaine d’atomes d’argent. Une étude spectrale a été réalisée permettant de distinguer les différents types d’agrégats générés. Par ailleurs, la génération de seconde harmonique est attribuée à la présence d’un champs électrique enterré dans la zone irradié par effet EFISH (electric field induced second harmonic). La direction et la répartition de ce champ électrique, ont été étudié optiquement et conduisent à sa représentation spatiale.Les effets des paramètres expérimentaux, tels que le nombre d’impulsions laser, l’énergie par impulsion, la température du verre et le recuit sur les caractéristiques de la GSH et de la fluorescence, ont été étudiés. Enfin un processus global est proposé, expliquant les différentes étapes de la structuration, de la création du champ enterré par migration d’électrons à la réduction des cations d’argent et la croissance des agrégats.In this work, a phosphate-zinc glass doped with silver ions was irradiated with a femtosecond laser. This irradiation causes the appearance of sub-micron features in the glass. Those features exhibit fluorescence and second harmonic generation. Fluorescence is linked to the aggregations of silver clusters in the glass. Second Harmonic Generation is linked to the creation of a buried electric field inducing an EFISHG effect.Polarization and spectroscopic studies were performed on these features. Those studies allowed us to produce a three-dimensional representation of the features. A phenomenological model, from the interaction of the laser pulses with the glass, to the movement of charges enabling the buried field, is developed to explain the overall process, therefore linking the migration of the electrons to the reduction of silver ion and the cluster growth

Nanostructuring of linear and non-linear properties of a photosensitive glass by femtosecond laser

Dans le cadre de cette thèse un verre phosphate de zinc dopé avec des cations d’argent a été irradié par laser femtoseconde. Cette irradiation induit l’apparition dans le voxel de focalisation, d’une émission de fluorescence et une génération de second harmonique au sein du verre. La fluorescence a été attribuée à la création d’agrégats fluorescents composé d’une dizaine d’atomes d’argent. Une étude spectrale a été réalisée permettant de distinguer les différents types d’agrégats générés. Par ailleurs, la génération de seconde harmonique est attribuée à la présence d’un champs électrique enterré dans la zone irradié par effet EFISH (electric field induced second harmonic). La direction et la répartition de ce champ électrique, ont été étudié optiquement et conduisent à sa représentation spatiale.Les effets des paramètres expérimentaux, tels que le nombre d’impulsions laser, l’énergie par impulsion, la température du verre et le recuit sur les caractéristiques de la GSH et de la fluorescence, ont été étudiés. Enfin un processus global est proposé, expliquant les différentes étapes de la structuration, de la création du champ enterré par migration d’électrons à la réduction des cations d’argent et la croissance des agrégats.In this work, a phosphate-zinc glass doped with silver ions was irradiated with a femtosecond laser. This irradiation causes the appearance of sub-micron features in the glass. Those features exhibit fluorescence and second harmonic generation. Fluorescence is linked to the aggregations of silver clusters in the glass. Second Harmonic Generation is linked to the creation of a buried electric field inducing an EFISHG effect.Polarization and spectroscopic studies were performed on these features. Those studies allowed us to produce a three-dimensional representation of the features. A phenomenological model, from the interaction of the laser pulses with the glass, to the movement of charges enabling the buried field, is developed to explain the overall process, therefore linking the migration of the electrons to the reduction of silver ion and the cluster growth

Three-Dimensional Direct Femtosecond Laser Writing Of Second-Order Nonlinearities In Glass

The microstructure evolution and mechanical properties of Al-20Si alloy with Sc addition were investigated after as-atomized and hot-extruded conditions. Microstructural and spectroscopic analyses demonstrate that Sc is enriched at the Si/Al interface. It could be observed that the presence of Sc refined the size of the primary and eutectic Si, without significantly affecting the shape. A considerable improvement in tensile strength, compressive strength, and elongation was observed due to addition in Sc percentage into the composition. The correlation between the microstructure and mechanical behavior strongly indicates that the addition of Sc modifies the Si particles by impurity induced twinning (IIT) mechanisms. © 2011 Elsevier B.V. All rights reserved

Direct Laser Writing Of Nonlinear Properties In Photosensitive Glass

A 1030 nm pulsed femtosecond laser has been use to induce modifications in silver containing glass namely femto-photo luminescent glass (FPL) and Photo-thermo refractive glass (PTR). The 5W 10Mhz laser is focused at a depth of 200 μm in the glass using a 0,52 NA objective. The output polarization of the laser is TM. The tailoring of the number of pulses, pulse energy and repetition rate is achieve by acousto-optic filtering. The interaction resulted in the creation of stable pipe-shaped silver clusters forming bellow refraction-limit 3D structures. Those nano-structures exhibit non-linear properties such as SHG and THG as well as fluorescence. Due to multiphoton absorption, free electrons are created in the central part of the beam, enabling the reduction of Ag+ silver ions into Ag0 and subsequently AgmX+. The cumulated thermal effect of the pulses weakens the glass matrix allowing the diffusion of the Ag mX+. The ion concentration gradient creates a buried electric field enabling non-linear properties. Influences of polarization, dose and fluence on the nonlinear properties are investigated. Our explanation of the causes of SHG and THG are validated by the accordance between the theory and the measurement. Comparisons between theoretic model and our results showing accordance in the limits of out 2D model are demonstrated using different incoming polarizations. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE)

Silver Clusters Embedded in Glass as a Perennial High Capacity Optical Recording Medium

International audienc

Fluorescence and second-harmonic generation correlative microscopy to probe space charge separation and silver cluster stabilization during direct laser writing in a tailored silver-containing glass

We report on fluorescence and second-harmonic generation correlative microscopy of femtosecond direct laser-induced structures in a tailored silver-containing phosphate glass. We compare the spatial distributions of the related permanent electric field and silver clusters. The latter appear to be co-localized where the associated electric potential ensures favorable reduction-oxidation conditions for their formation and stabilization. Space charge separation is shown to occur prior the cluster formation. The associated electric field is a key parameter for silver clustering, thanks to electric field assisted silver ion motion. Future photonic structures combining 3D laser-structured fluorescence and nonlinear optical properties in such tailored glass will require an optimal control of the induced electric field distribution.Femtosecond Laser Interaction and Nanostructurin

Fluorescence and second-harmonic generation correlative microscopy to probe space charge separation and silver cluster stabilization during direct laser writing in a tailored silver-containing glass

We report on fluorescence and second-harmonic generation correlative microscopy of femtosecond direct laser-induced structures in a tailored silver-containing phosphate glass. We compare the spatial distributions of the related permanent electric field and silver clusters. The latter appear to be co-localized where the associated electric potential ensures favorable reduction-oxidation conditions for their formation and stabilization. Space charge separation is shown to occur prior the cluster formation. The associated electric field is a key parameter for silver clustering, thanks to electric field assisted silver ion motion. Future photonic structures combining 3D laser-structured fluorescence and nonlinear optical properties in such tailored glass will require an optimal control of the induced electric field distribution.Femtosecond Laser Interaction and Nanostructurin

Fluorescence and second-harmonic generation correlative microscopy to probe space charge separation and silver cluster stabilization during direct laser writing in a tailored silver-containing glass

We report on fluorescence and second-harmonic generation correlative microscopy of femtosecond direct laser-induced structures in a tailored silver-containing phosphate glass. We compare the spatial distributions of the related permanent electric field and silver clusters. The latter appear to be co-localized where the associated electric potential ensures favorable reduction-oxidation conditions for their formation and stabilization. Space charge separation is shown to occur prior the cluster formation. The associated electric field is a key parameter for silver clustering, thanks to electric field assisted silver ion motion. Future photonic structures combining 3D laser-structured fluorescence and nonlinear optical properties in such tailored glass will require an optimal control of the induced electric field distribution.Femtosecond Laser Interaction and Nanostructurin

Femtosecond single-beam direct laser poling of stable and efficient second-order nonlinear optical properties in glass

We depict a new approach for the localized creation in three dimensions (3D) of a highly demanded nonlinear optical function for integrated optics, namely second harmonic generation. We report on the nonlinear optical characteristics induced by single-beam femtosecond direct laser writing in a tailored silver-containing phosphate glass. The original spatial distribution of the nonlinear pattern, composed of four lines after one single laser writing translation, is observed and modeled with success, demonstrating the electric field induced origin of the second harmonic generation. These efficient second-order nonlinear structures...Femtosecond Laser Interaction and Nanostructurin