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Photonic Devices (photonic + device)
Selected AbstractsExcitation dynamics in a three-quantum dot system driven by optical near-field interaction: towards a nanometric photonic deviceJOURNAL OF MICROSCOPY, Issue 3 2003K. Kobayashi Summary Using density operator formalism, we discuss interdot excitation energy transfer dynamics driven by the optical near-field and phonon bath reservoir, as well as coherent excitation dynamics of a quantum dot system. As an effective interaction between quantum dots induced by the optical near-field, the projection operator method gives a renormalized dipole interaction, which is expressed as a sum of the Yukawa functions and is used as the optical near-field coupling of quantum dots. We examine one- and two-exciton dynamics of a three-quantum dot system suggesting a nanometric photonic switch, and numerically obtain a transfer time comparable with the recent experimental results for CuCl quantum dots. [source] New Insights on Near-Infrared Emitters Based on Er-quinolinolate Complexes: Synthesis, Characterization, Structural, and Photophysical Properties,ADVANCED FUNCTIONAL MATERIALS, Issue 14 2007F. Artizzu Abstract Erbium quinolinolates, commonly assumed to be mononuclear species with octahedral co-ordination geometry, have been proposed as promising materials for photonic devices but difficulties in obtaining well defined products have so far limited their use. We report here the conditions to obtain in high yields three different kinds of pure neutral erbium quinolinolates by mixing an erbium salt with 8-quinolinol (HQ) and 5,7-dihalo-8-quinolinol (H5,7XQ: X,=,Cl and Br): i),the trinuclear complex Er3Q9 (1) which is obtained with HQ deprotonated by NH3 in water or ethanol/water mixtures; ii),the already known dimeric complexes based on the unit [Er(5,7XQ)3(H2O)2] [X,=,Cl (2) and Br (3)]; iii) the mononuclear [Er(5,7XQ)2(H5,7XQ)2Cl] [X,=,Cl (4) and Br (5)] complexes, obtained in organic solvents without base addition, where the ion results coordinated to four ligands, two deprotonated chelating, and two as zwitterionic monodentate oxygen donors. These results represent a further progress with respect to a recent reinvestigation on this reaction, which has shown that obtaining pure and anhydrous octahedral ErQ3, the expected reaction product, is virtually impossible, but failed in the isolation of 1 and of the neutral tetrakis species based on H5,7XQ ligands. Structural data provide a detailed description of the molecules and of their packing which involves short contacts between quinoxaline ligands, due to ,,, interactions. Electronic and vibrational studies allow to select the fingerprints to distinguish the different products and to identify the presence of water. The structure/property relationship furnishes a satisfactory interpretation of the photo-physical properties. Experimental evidence confirms that the most important quenchers for the erbium emission are the coordinated water molecules and shows that the ligand emission is significantly affected by the ,,, interactions. [source] Highly Non-Linear Quantum Dot Doped Nanocomposites for Functional Three-Dimensional Structures Generated by Two-Photon PolymerizationADVANCED MATERIALS, Issue 22 2010Baohua Jia A nanocomposite consisting of a photosensitive organic,inorganic hybrid polymer functionalized with PbS quantum dots has been developed using a sol,gel process. The uniformly dispersed nanocomposite exhibits ultrahigh third-order non-linearity (,3.2,×,10,12 cm2 W,1) because of the strong quantum confinement of small-sized and narrowly distributed quantum dots. The non-linear nanocomposite has been proven to be suitable for the fabrication of 3D micro/nano photonic devices using two-photon polymerization. The fabricated photonic crystals show stop gaps with more than 60% suppression in transmission at the telecommunications wavelength region. [source] The Synthesis and Assembly of Polymeric Microparticles Using MicrofluidicsADVANCED MATERIALS, Issue 41 2009Dhananjay Dendukuri Abstract The controlled synthesis of micrometer-sized polymeric particles bearing features such as nonspherical shapes and spatially segregated chemical properties is becoming increasingly important. Such particles can enable fundamental studies on self-assembly and suspension rheology, as well as be used in applications ranging from medical diagnostics to photonic devices. Microfluidics has recently emerged as a very promising route to the synthesis of such polymeric particles, providing fine control over particle shape, size, chemical anisotropy, porosity, and core/shell structure. This progress report summarizes microfluidic approaches to particle synthesis using both droplet- and flow-lithography-based methods, as well as particle assembly in microfluidic devices. The particles formed are classified according to their morphology, chemical anisotropy, and internal structure, and relevant examples are provided to illustrate each of these approaches. Emerging applications of the complex particles formed using these techniques and the outlook for such processes are discussed. [source] Organic Electro-optic Single- Crystalline Thin Films Grown Directly on Modified Amorphous Substrates,ADVANCED MATERIALS, Issue 3 2008O-P. Kwon High quality organic electro-optic single crystalline thin films are produced on amorphous C,N-modified glass substrates (see figure), which is a mimic surface of a crystal, by slow evaporation and capillary methods. The films have a suitable size (shaped as rectangular plates with side lengths in the range of 5,10 mm and regular thicknesses in the range of 1,40 ,m) for the fabrication of photonic devices. [source] A Novel Macromolecular Complex: Fabrication of Monodisperse Colloidal Microspheres by Precipitation Polymerization of Imine Chains and Concomitant Transition Metal BindingADVANCED MATERIALS, Issue 17 2003H. Houjou A series of monodisperse colloidal microspheres has been fabricated by precipitation polymerization of imine chains and concomitant transition metal binding. The resulting metal-bound polyimine microspheres (M-PIMSs, M = Co, Ni, Cu, or Zn, see Figure, which shows Zn-PIMSs) have characteristic diameters in the range from 0.5 to 1.4 ,m, depending on the metal used, and are of interest for applications in photonic devices. [source] Poly(3,4-ethylenedioxythiophene) Nanospheres Synthesized Using a Micelle Soft Template Associated with Cuprous OxideMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 11 2010Ying Zhu Abstract PEDOT nanospheres with an average diameter of about 100,nm were chemically synthesized using APS as the oxidant in the presence of SDBS and Cu2O, respectively. It was found that Cu2O is crucial to forming uniform PEDOT nanospheres because only granular PEDOT was obtained in the absence of Cu2O. It is proposed that the PEDOT nanospheres are self-assembled by a cooperation effect of SDBS as the micelle soft-template and Cu2O as the stabilizer of the spherical micelles. Additionally, the PEDOT nanospheres are soluble in some organic solvents, such as THF, DMF and DMSO, which is of benefit for fabrication of electronic and photonic devices. [source] A hybrid approach towards nanophotonic devices with enhanced functionalityPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2009Michael Barth Abstract We introduce a hybrid approach for the realization of nanophotonic devices with enhanced functionality by combining lithographic fabrication techniques with a nanomanipulation method. In particular, we report on the fabrication of photonic crystal cavities as a platform to which arbitrary emitters or other nanoscopic objects can be coupled in a deterministic way by exploiting the manipulation capabilities of an atomic force microscope. This approach is well suited to create, e.g., improved single photon sources and also complex photonic devices with several emitters coupled coherently via shared cavity modes. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] High-performance nanoparticle-enhanced tunnel junctions for photonic devicesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2010Adam M. Crook Abstract We describe GaAs-based tunnel junctions that are compatible with photonic devices, including long-wavelength vertical-cavity surface-emitting lasers and multi-junction solar cells. Tunneling was enhanced with semimetallic ErAs nanoparticles, particularly when grown at reduced substrate temperatures. Additionally, we present the first direct measurement of the quality of III-V layers grown above ErAs nanoparticles. Photoluminescence measurements indicate that III-V material quality does not degrade when grown above ErAs nanoparticles, despite the mismatch in crystal structures. These findings validate these tunnel junctions as attractive candidates for GaAs-based photonic devices (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Toward control of point defects in lithium fluoride thin layersPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2007R. M. Montereali Abstract Point defect formation and stabilization properties, as well as their peculiar spectroscopic characteristics, locally modify the optical properties of insulating materials. Thin layers containing high concentrations of colour centres, hosted in a LiF single crystal and/or a polycrystalline matrix, offer the opportunity to develop innovative light-emitting photonic devices. Control of all the critical parameters should be required on spatial dimension comparable with the optical wavelengths. Recent developments in laser technologies, electron and particles beam methods, and novel photon sources, have opened a wide range of opportunities. An overview of the most significant advances in this field is provided, with particular emphasis on colour-centre LiF-based innovative miniaturised light sources, optical amplifiers and lasers. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nanofabrication of aligned conducting polymers,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9-10 2006Muge Acik Abstract Poly(pyrrole), poly(N-methyl pyrrole), poly(thiophene) and poly(3,4-ethylenedioxythiophene) nano-arrays, nano-fibers and nano-tubes have been successively synthesized using polycarbonate and alumina membranes as templates. Oxidative chemical polymerization method was used to produce nano-structured conducting polymers with diameters in the range of 80,350 nm and the size of the resulting polymer was controlled with the pore size of membrane. Preliminary results showed that highly oriented polymers are promising materials for many applications including supercapacitors, sensors and photonic devices. Copyright © 2006 John Wiley & Sons, Ltd. [source] Anisotropic distribution of quantum-vacuum momentum density in a moving electromagnetic mediumANNALEN DER PHYSIK, Issue 7 2010J.Q. Shen Abstract An isotropic electromagnetic medium becomes gyrotropically anisotropic when it moves, and an anisotropic electromagnetic environment can then be created in this motion-induced anisotropic medium. One of the most remarkable features is that the quantum vacuum in the anisotropic electromagnetic environment exhibits a nonzero electromagnetic momentum density, since the universal symmetry of the vacuum fluctuation field is broken, and the anisotropic quantum vacuum mode structure is produced because of the symmetry breaking. This would give rise to a noncompensation effect among the four vacuum eigenmodes (i.e., the forward and backward propagating modes as well as their respective mutually perpendicular polarized components), and leads to an anisotropic correction to the vacuum momentum in the moving medium. The physical significance and the potential applications of the anisotropic quantum vacuum are discussed. This quantum-vacuum effect may be used to develop sensitive sensor techniques and to design new quantum optical and photonic devices. [source] Single-Step Electron Transfer on the Nanometer Scale: Ultra-Fast Charge Shift in Strongly Coupled Zinc Porphyrin,Gold Porphyrin DyadsCHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2008Jérôme Fortage Dr. Abstract The synthesis, electrochemical properties, and photoinduced electron transfer processes of a series of three novel zinc(II),gold(III) bisporphyrin dyads (ZnPSAuP+) are described. The systems studied consist of two trisaryl porphyrins connected directly in the meso position via an alkyne unit to tert -(phenylenethynylene) or penta(phenylenethynylene) spacers. In these dyads, the estimated center to center interporphyrin separation distance varies from 32 to 45,Å. The absorption, emission, and electrochemical data indicate that there are strong electronic interactions between the linked elements, thanks to the direct attachment of the spacer on the porphyrin ring through the alkyne unit. At room temperature in toluene, light excitation of the zinc porphyrin results in almost quantitative formation of the charge shifted state .+ZnPSAuP., whose lifetime is in the order of hundreds of picoseconds. In this solvent, the charge-separated state decays to the ground state through the intermediate population of the zinc porphyrin triplet excited state. Excitation of the gold porphyrin leads instead to rapid energy transfer to the triplet ZnP. In dichloromethane the charge shift reactions are even faster, with time constants down to 2,ps, and may be induced also by excitation of the gold porphyrin. In this latter solvent, the longest charge-shifted lifetime (,=2.3,ns) was obtained with the penta-(phenylenethynylene) spacer. The charge shift reactions are discussed in terms of bridge-mediated super-exchange mechanisms as electron or hole transfer. These new bis-porphyrin arrays, with strong electronic coupling, represent interesting molecular systems in which extremely fast and efficient long-range photoinduced charge shift occurs over a long distance. The rate constants are two to three orders of magnitude larger than for corresponding ZnPAuP+ dyads linked via meso -phenyl groups to oligo-phenyleneethynylene spacers. This study demonstrates the critical impact of the attachment position of the spacer on the porphyrin on the electron transfer rate, and this strategy can represent a useful approach to develop molecular photonic devices for long-range charge separations. [source] | |||||||||||||