Lionel Canioni

Silver clusters embedded in glass as a perennial high capacity optical recording medium.

[∗] Dr. A. Royon , Dr. M. Bellec , G. Papon , Dr. B. Bousquet , Prof. L. Canioni Centre de Physique Moleculaire Optique et Hertzienne University of Bordeaux 351 Cours de la Liberation, 33405 Talence (France) E-mail: l.canioni@cpmoh.u-bordeaux1.fr K. Bourhis , Dr. T. Cardinal Institut de Chimie de la Matiere Condensee de Bordeaux University of Bordeaux 87 Avenue du Docteur Schweitzer, 33608 Pessac (France) Dr. Y. Deshayes Laboratoire de l ′ Integration du Materiau au Systeme University of Bordeaux 351 Cours de la Liberation, 33405 Talence (France)

Optical non-linearity in oxide glasses

The origin of the optical non-linear response has been investigated in two different types of oxide glasses. Linear and non-linear refractive indices have been obtained by interferometric measurements. Correlations between the local structure of polarizable entities within glasses and their optical activities have been tentatively established through ab initio calculations.

Nonlinear optical properties of some tellurium (IV) oxide glasses

Abstract Thermal and optical properties of glasses of the TeO 2 | ZnO, TeO 2 | Nb 2 O 5 and TeO 2 | M 2 O | Nb 2 O 5 (M = Li, K) systems have been investigated. Linear and nonlinear indices of the materials increase with the TeO 2 rate. The highest values are obtained for the niobium tellurite glasses emphasizing the particularly significant role of NbO 6 octahedra in the optical response.

Three-dimensional optical data storage using third-harmonic generation in silver zinc phosphate glass

We demonstrate the possibility of three-dimensional optical data storage inside a specific zinc phosphate glass containing silver by using third-harmonic generation (THG) imaging. Information is stored inside the glass with femtosecond laser irradiation below the refractive index modification threshold. We use the same laser for THG readout. The capability of storage with this technique is discussed.

Beat the diffraction limit in 3D direct laser writing in photosensitive glass

Three-dimensional (3D) femtosecond laser direct structuring in transparent materials is widely used for photonic applications. However, the structure size is limited by the optical diffraction. Here we report on a direct laser writing technique that produces subwavelength nanostructures independently of the experimental limiting factors. We demonstrate 3D nanostructures of arbitrary patterns with feature sizes down to 80 nm, less than one tenth of the laser processing wavelength. Its ease of implementation for novel nanostructuring, with its accompanying high precision will open new opportunities for the fabrication of nanostructures for plasmonic and photonic devices and for applications in metamaterials.

Femtosecond laser induced photochemistry in materials tailored with photosensitive agents [Invited]

This article deals with the recent advances in photochemistry in optical materials induced by femtosecond laser pulses. The field of investigation of this paper is limited to bulk solid isotropic transparent materials (glasses and polymers), specifically tailored with photoactive agents. The formation mechanisms of laser-induced color centers, nanoclusters, nanoparticles and nanocrystallites are reviewed and argued, in particular the influence of the temperature during or after the laser irradiation. The relation between the photo-induced structures and the optical property modifications are discussed, as well as some applications.

Optical properties of infrared femtosecond laser-modified fused silica and application to waveguide fabrication

We investigate the changes in the optical properties of fused silica exposed to intense infrared femtosecond pulses. The laser-induced absorption spectrum reveals the creation of color centers inside the glass matrix, comparable with those observed in ultraviolet-exposed fused silica. The laser-induced absorption is associated with a laser-induced refractive-index change, which can be used for waveguide fabrication. The change in third-order susceptibility in such waveguides is measured by third-harmonic-generation microscopy as a function of the irradiation parameters.

Propagation beam consideration for 3D THz computed tomography

In this paper, a model of the beam propagation is developed according to the physical properties of THz waves used in THz computed tomography (CT) scan imaging. This model is first included in an acquisition simulator to observe and estimate the impact of the Gaussian beam intensity profile on the projection sets. Second, the model is introduced in several inversion methods as a convolution filter to perform efficient tomographic reconstructions of simulated and real acquired objects. Results obtained with three reconstruction methods (BFP, SART and OSEM) are compared to the techniques proposed in this paper. We will demonstrate an increase of the overall quality and accuracy of the 3D reconstructions.

Imaging of Ca(2)+ intracellular dynamics with a third-harmonic generation microscope.

We describe the promising development of third-harmonic generation (THG) in laser scanning microscopy for study of the functional imaging of live biological cells. The dynamics of Ca(2+) in biological cells is shown. The Ca(2+) signal consists of a transient increase in the intracellular concentration. THG microscopy allows one to temporally visualize the release of Ca(2+) from internal stores and (or) calcium influx.

Chemometrics Applied to Quantitative Analysis of Ternary Mixtures by Terahertz Spectroscopy

Chemometrics was applied to qualitative and quantitative analyses of terahertz spectra obtained in transmission mode. A series of mixtures of three pure analytes, namely, citric acid, D-(-)fructose, and α-lactose monohydrate under various concentrations, was prepared as pressed pellets with polyethylene as binder. Then, terahertz absorbance spectra were recorded by terahertz time domain spectroscopy and analyzed. First, principal component analysis allowed one to correctly locate the samples into a ternary diagram. Second, quantitative analysis was achieved by partial least-squares (PLS) regression and artificial neural networks (ANN). The concentrations were predicted with values of relative mean square error lower than 0.9% for the three constituents. As a conclusion, chemometrics was demonstrated to be very efficient for the analysis of the ternary mixtures prepared for this study.