For a few years semiconductor quantum dots have attracted a lot of interest. To be part of photonic structures quantum dots are generally embedded in thin films. After briefly reviewing the application fields, a simple model for 2D structured is presented. Examples of recent results concerning optical properties of poly(methyl methacrylate) (PMMA) thin films containing CdSe/ZnS and TiO2 quantum dots are given describing their reflection, transmission, absorption and photoluminescence. The problem of the refractive index of thin films containing quantum dots and of quantum dots alone is also addressed.

A long list of philosophers/scientists allowed understanding the nature of light and of its interaction with matter, the development of optical instruments and of lasers. We can briefly cited some of them who are known to bring important steps in these progresses. By trying to explain vision, Greek like Euclid (300 B.C.), Hero (60 A.D.), Ptolemy (120 A. D.) and then the Arab scientist Alhazen (1000 A.D.) described light propagation, till 13th century Italian glassworkers made lenses that were used for spectacles. Kepler (1604) decribed the propagation of light through lenses with geometrical optics, and he applied his studies to the eye. Lippershey invented the telescope soon before Galileo (1609) produced his own telescope and started to study planets and moons. Snell, Descartes(~1637), Newton (~1704) , Grimaldi (~1665), Huygens (~1690), Euler (1746), Gauss (~1800), Young (1803), Fraunhofer(1814), Fresnel (1819) , Abbe (1887)... allowed to deepen the understanding of classical optics by extending the notion of rays to the notion of waves.

The extraordinary progresses in the design and realization of structures in inorganic or organic thin films, whether or not including nanoparticles, make it possible to develop devices with very specific properties. Mastering the links between the macroscopic optical properties and the optogeometrical parameters of these heterogeneous layers is thus a crucial issue. We propose to present the tools used to characterize and to model thin film layers, from an optical point of view, highlighting the interest of coupling both experimental and simulation studies for improving our knowledge on the optical response of the structure. Different examples of studies are presented on copper indium gallium selenide, perovskite, P3HT:ZnO, PC70BM, organic layer containing metallic nanoparticles, and colored solar cells. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)

Nowadays in laboratories and in industries, distribution of solar cells sizes could be very large, hence; for the first time it is rather difficult to compare photovoltaic parameters which are size dependent (current, serial resistance, shunt resistance...) and performances of these cells. Also, it will be useful for scale effect to extrapolate performances calculated on a unit size solar cell to commercial products, especially in the case of heterogeneous wafers used for the device.

The extraordinary progresses in the design and realization of structures in inorganic or organic thin films, whether or not including nanoparticles, make it possible to develop devices with very specific properties. Mastering the links between the macroscopic optical properties and the opto-geometrical parameters of these heterogeneous layers is thus a crucial issue. We propose to present the tools used to characterize and to model thin film layers, from an optical point of view, highlighting the interest of coupling both experimental and simulation studies for improving our knowledge on the optical response of the structure. Different examples of studies are presented on CIGS, Perovskite, P3HT:ZnO, PC70BM, organic layer containing metallic nanoparticles and colored solar cells.

The synthesis of a conformal poly(3,4-ethylenedioxythiophene) (PEDOT) layer on Si nanowires was demonstrated using a pulsed electrodeposition technique. N-type Si nanowire (SiNWs) arrays were synthesized using an electroless metal-assisted chemical etching technique. The dependence of the SiNW reflection on the concentration of the AgNO3 solution was identified. A reflection of less than 2% over the entire visible spectral range was obtained for these structures, evidencing their excellent antireflective properties. The etched SiNWs nanostructures can be further modified by using a tapering technique, which further preserves the strong light trapping effect. P-type PEDOT was grown on these SiNWs using electrochemical methods. Since the polymerization reaction is a very fast process with regards to monomer diffusion along the SiNW, the conformal deposition by classical, fixed potential deposition was not favored. Instead, the core–shell heterojunction structure was finally achieved by a pulsed deposition method. An extremely large shunt resistance was exhibited and determined to be related to the diffusion conditions occurring during polymerization.

This article addresses the main results of the PEPS (PEllet Photonic Sensor) project, whcich aims at developing a new gas sensing transducer via a technological breakthrough: the combination of photonics (insensitive to external electromagnetic disturbances) and catalysis (reversibility, limited energy consumption). Indeed, catalytic reactions are often exothermic and this heat can modify the properties of optical devices. The experimental studies performed during the PEPS project highlighted the rapid and reversible response at room temperature of catalytic powders towards different concentrations of H2 in air. The thermal and optical properties of the materials used for the integrated photonic component have also been studied. These results have been exploited for the design of the photonic transducers. The feasibility of the physical transduction principle has been demonstrated by developing different prototypes based on Bragg gratings and Multimode Interference Components.

We propose a method under the effective mass approximation with an original formulation that applies to quantum wells, circular quantum wires, and spherical quantum dots of arbitrary materials with sizes as small as 1 nm. Hundreds of structures are resolved on the second scale on a laptop, allowing for optimization procedures. We demonstrate its capability by confronting bandgap calculations with exhaustive literature data for CdS, CdSe, PbS, and PbSe nanoparticles. Our approach includes a correction of the mass to address the nonparabolicity of the band structure. The correction gives an accuracy comparable to more demanding calculation methods, such as eight-band k center dot p, tight-binding, or even semiempirical pseudopotential methods. The effect of the correction is shown on the intrasubband optical properties of InGaAs/ AlGaAs coupled quantum wells. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)

The optical properties of core-shell quantum dots (QDs) are important for optoelectronic devices and biological applications. In this study, we investigate the optical properties of core-shell CdSe/ZnS QDs embedded in PMMA polymer thin films. The luminescence from QD emission would be more applicable if the spatial distribution of the emission was controllable. We propose a method to control the emission distribution by modifying the nanostructure. A bi-periodic nanostructure was fabricated and characterized in hybrid QD thin films by a nano-imprint technique. The finite difference time domain method was used to simulate the electric field distribution in the measured structure. It is shown that the far-field distribution of the QD emission is controllable by manipulating the nanostructure of the hybrid QD thin films.

We present an improved and efficient numerical method to determine the optical properties of nanostructures starting from the electronic properties. We study the variation of electronic and optical properties induced by confinement effects in semiconductors quantum objects. We solve the time-independent Schrodinger equation with a new formulation of a shooting method under the effective mass approximation. This formulation is adapted to quantum wells, circular cross-section quantum wires and spherical quantum dots. We applied a correction on the mass to take into account the nonparabolicity of the band structure. The correction gives an accuracy comparable to more demanding calculation methods such as 8-bands k.p, tight binding or even semi-empirical pseudopotential methods. Our results remain valid even for low-bandgap materials and sizes as small as 1 nm. The calculation speed of our method allows optimization procedures that give better understanding of experimental results concerning CdS, CdSe, PbS and PbSe spherical quantum dots. We consider extensive data from the literature. We focus on the relations between the electronic structure and absorption and photoluminescence spectra measured on spin-coated PMMA thin-films containing (core)shell nanoparticles.

Scientific and technical innovations take place in many laboratories. There can be a lot of ground to cover from an innovative concept to an industrial product commercialized by a company. Different processes have been implemented in France to develop a real ecosystem to facilitate this process. Photonics clusters, incubators, start-up nurseries and technology transfer structures are working together with funding structures like business angels and with some public support. To illustrate the process, an example of a photonics concept applied to develop accurate and selective gas sensors will also be presented along with the approach used.

Thanks to progresses in material science and nanotechnologies, surfaces and thin films can now be structured at different scales. Photonics components take benefit of this possibility to fulfill still more and more complex functions. They are composed as well of organic as inorganic materials, dielectric, semiconductor, and metallic materials, or a mixture of them. Multiscale and chiral structures can be used to control both spectral, spatial distribution of light together with its polarization state. The optical mode density in the near field and in the far field can then be designed in particular by combining more or less resonant structures for the optical waves, associating diffraction, interferences and anisotropic structures like Fabry-Perot, waveguide, plasmons, photonic crystals... Artificially nanostructured materials often called metamaterials exhibit new properties. Different phenomena recently considered, including optical topological insulator and structures for vortex waves transporting angular momentum of photons, will be also discussed and illustrated. With the development of nanometer size structures another step is overtaken allowing the control of the intimate interaction of optical waves with materials to tune their basic electronic properties and permittivity. Both optical and electronic properties are also strongly dependent on coupling effects needing a global approach.

The deformed potential structure of CdSe/ZnS core/shell quantum dots (QDs) was analyzed by calculating precise state energies and state functions. Exactly how an external electric field affects the photoluminescence was also studied. Additionally, the tilt potential structure induced by the external electric field, commonly referred to as the quantum-confined Stark effect, was calculated to account for the observed blue and red shifts. Experimental results indicated that the deformation also includes a bend, which is attributed to the shape of a QD. Calculations of the localization of electrons of the foregoing phenomena closely correspond to the experimental data. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)

Sol-gel applications require very thick layers with a good understanding of the interfaces. To address this problem, we have installed at CEA Le Ripault a characterization bench using guided waves with assistance from the IM2NP lab in Marseille. This bench allows us to measure the thickness and the refractive index and determine the extinction coefficient of a thin layer. We can distinguish losses at interfaces from those in the bulk according to the chosen propagation mode. This allows us to know if we can stack elementary layers to make thick layers without incurring problems.

We present a soft method for the fabrication of well controlled plasmonic nanodots on large ITO substrate for organic solar cells. Masks of nanopatterned aluminum oxide are elaborated and deposited on ITO substrates before metal deposition. After removal of the mask, well organized and isolated metallic nanodots are observed. In this article, we focus on gold or silver nanostructures: they show a Surface Plasmon Resonance (SPR) in the visible region, an important feature for their integration in organic thin film solar cells and the final improvement of the optical properties of the cell. In addition, their near field enhancement capacity is also clearly demonstrated by surface enhanced Raman spectroscopy and FDTD method simulation. An additional advantage of this protocol is that it can be used on any kind of surface and with different metals, depending on the final application.