Hazy Al₂O₃-FTO Nanocomposites: A Comparative Study with FTO-Based Nanocomposites Integrating ZnO and S:TiO₂ Nanostructures.

In this study, we report the use of Al₂O₃ nanoparticles in combination with fluorine doped tin oxide (F:SnO₂, aka FTO) thin films to form hazy Al₂O₃-FTO nanocomposites. In comparison to previously reported FTO-based nanocomposites integrating ZnO and sulfur doped TiO₂ (S:TiO₂) nanoparticles (i.e.

Three-Dimensional Self-Organization in Nanocomposite Layered Systems by Ultrafast Laser Pulses.

Controlling plasmonic systems with nanometer resolution in transparent films and their colors over large nonplanar areas is a key issue for spreading their use in various industrial fields. Using light to direct self-organization mechanisms provides high-speed and flexible processes to meet this challenge. Here, we describe a route for the laser-induced self-organization of metallic nanostructures in 3D.

HAADF-STEM characterization and simulation of nanoparticle distributions in an inhomogeneous matrix.

Measuring with a high accuracy the size distribution of small metallic nanoparticles loaded in a mesoporous metal oxide matrix is of particular interest for many studies related to new generations of interesting metamaterials. Transmission electron microscopy (TEM) is a powerful tool to determine the nature and morphology of very small particles, but their reliable and automatic identification in an inhomogeneous environment where the nanoparticle/background contrast locally varies is not straightforward. Here, we present how a quantitative analysis of high-angle annular dark field scanning TEM (HAADF STEM) images, accounting for the chemical sensitivity of the technique, can improve the accuracy of semiautomatic segmentation methods based on morphological processing to calculate size histograms.

Laser induced mechanisms controlling the size distribution of metallic nanoparticles.

This paper describes a model to simulate changes in the size distribution of metallic nanoparticles (NPs) in TiO2 films upon continuous wave light excitation. Interrelated laser induced physical and chemical processes initiated directly by photon absorption or by plasmon induced thermal heating are considered. Namely the model takes into account the NP coalescence, Ostwald ripening, the reduction of silver ions and the oxidation of metallic NPs, competitive mechanisms that can lead to counter-intuitive behaviors depending on the exposure conditions.

Angular and polarization properties of cross-holes nanostructured metallic filters.

It has been shown in literature that cross-shaped holes arrays can be made insensitive to polarization at normal incidence, and can even feature good stability for off-normal incidence. In this work we look for the optimal design rules to obtain high spectral stability conditions in the visible for those structures, through a complete review of all geometrical parameters using CMOS-compatible materials. Rigorous Coupled Wave Analysis (RCWA) simulations have been used to identify the most-impacting parameters and to determine typical ranges allowing for the realization of low-color errors image sensors whatever the light incidence.

Obstructive micro diffracting structures as an alternative to plasmonics nano slits for making efficient microlenses.

Miniature optical components at the wavelength scale remain today a theoretically opened challenging problem of great technological interest. Appart from refractive micro-optics, plasmonics have been proposed to realize micro lenses with properly designed planar metallic nano-patterns. We show in this paper that efficient light focusing at the diffraction limit with higher transmission can be obtained with micro-structures much easier to fabricate than nano ones, such as a simple micro-slit studied here as an example.

Simultaneous passively Q-switched dual-wavelength solid-state laser working at 1065 and 1066 nm.

A passively Q-switched dual-wavelength solid-state laser is presented. The two wavelengths are emitted by two different crystals in order to avoid gain competition, and the synchronization between the pulses is obtained by external triggering of the saturable absorber. Sum frequency mixing is demonstrated, proving the interest of this source for terahertz generation in the 0.

Metallic nanowires can lead to wavelength-scale microlenses and microlens arrays.

We theoretically and experimentally demonstrate that the diffraction of microstructures based on silver nanowires leads to very efficient microfocusing effects. Pairs of parallel nanowires act as ultrasmall cylindrical microlenses with diffraction-limited resolution in the Fresnel region. This is a new diffraction scheme to make micron-sized optical lenses with higher transmittance than plasmonic microlens based on nano-aperture arrays.

Optically driven Archimedes micro-screws for micropump application.

Archimedes micro-screws have been fabricated by three-dimensional two-photon polymerization using a Nd:YAG Q-switched microchip laser at 532nm. Due to their small sizes they can be easily manipulated, and made to rotate using low power optical tweezers. Rotation rates up to 40 Hz are obtained with a laser power of 200 mW, i.

Gold hollow spheres obtained using an innovative emulsion process: towards multifunctional Au nanoshells.

The tremendous development of materials with fine tuning of their composition, shape, size and chemical functionalities at the nanometer scale has opened a wide range of applications, particularly in medicine. Metallic nanoparticles are extremely interesting for such developments. The fundamental study of surface plasmon resonance (SPR) versus the shape/size of a particle is an important challenge.

Phase matching in ?erenkov second-harmonic generation: a leaky-mode analysis.

Use of leaky modes allows us to demonstrate very simply that ?erenkov second-harmonic generation is not free of phase matching. The ?erenkov phase-matching condition is derived for what is to our knowledge the first time. The way to overcome the difficulty linked with the divergence at infinity of the leaky modes is discussed.

Degenerate four-wave mixing geometry in thin-film waveguides for nonlinear material characterization.

We demonstrate experimentally a new degenerate four-wave mixing (DFWM) geometry in waveguides that permits the simultaneous determination of the nonlinear refractive index, the absorption, and the response time of the thin-film materials. The geometry consists of two guided pumps in a planar waveguide with an unguided probe. We achieve nonlinear characterization by measuring only the DFWM signal and the guided pump power at the waveguide output.

Fast optical switching in nonlinear prism couplers.

The excitation process of short optical pulses in waveguides by use of prism couplers is studied with a fully dynamic model. A good coupling efficiency is obtained even for short pulses. Fast nonlinear behavior such as power limiting and optical switching is predicted with a response time much shorter than the buildup time of the waveguide coupler.

Nonlinear prism coupling with nonlocality.

The characteristics of prism coupling of finite-width beams into nonlinear waveguides composed of media with diffusive nonlinearities (thermal, etc.) are calculated by including a one-dimensional diffusion equation for the nonlocal nonlinearity. The resulting longitudinal feedback leads to bistability, and the threshold value for the minimum diffusion length varies inversely with the angular detuning.