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Optical Transmission (optical + transmission)
Selected AbstractsImprovement of the Optical Transmission of Polymer Planar Waveguides by Plasma TreatmentPLASMA PROCESSES AND POLYMERS, Issue 3 2008Aissam Airoudj Abstract The aim of the present work is to reduce the optical losses of glycidyl ether of bisphenol A (SU-8) polymer planar waveguides using cold plasmas, which allow the substitution of H atoms by F. CF4 and mixtures of CF4/H2 RF plasma treatments were carried out for the surface fluorination of the SU-8 waveguide. The observed decrease in the optical losses due to propagation in the Si/SiO2/fluorinated SU-8 planar waveguides has been correlated with the surface fluorination as measured by XPS and CA measurements. In order to understand and to optimize the fluorination process, the plasma phase was analyzed by OES. Finally, the thickness of the fluorinated layer was estimated using modulated incident-angle XPS. [source] Spectral properties and thermoluminescence of codoped PbWO4:(Mo,Y) and PbWO4:(F,Y) crystalsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2009Jian-jun Xie Abstract Lead tungstate, PbWO4 single crystals codoped with Mo6+/F, and Y3+ ions were grown using the modified Bridgman method. Optical transmission, X-ray excited luminescence, photoluminescence, ultrashort pulsed X-ray excited fluorescent lifetime and thermoluminescence have been investigated. Compared to pure PbWO4, the codoped PbWO4:(Mo,Y) and PbWO4:(F,Y) crystals exhibit improved transmittance in the short-wavelength region. Luminescence and light-yield measurements demonstrated that Mo6+/F, and Y3+ codoping could enhance the luminescence of PbWO4 and reduce slow decay components. Doped Mo6+ and F, ions in PbWO4 were tentatively considered to occupy W and O sites, while Y3+ ions codoped in PbWO4:Mo/F mostly occupy Pb sublattice sites. The second excitation peak at 335 nm, which is the second effective excitation for the enhanced blue-green emission in as-grown PbWO4:(Mo,Y) and PbWO4:(F,Y) crystals, should be related to MoO42, groups and O vacancies (VO). Thermoluminescence glow curve measurement between RT and 400 °C provides complementary information about trapping states and the effect of Y3+ ion codoping resulting in the reduction of stable and temporary hole centers. Further work is needed to explain the doping and energy-transfer mechanism. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Properties of the fundamental absorption edge of InN crystals investigated by optical reflection and transmission spectraPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 12 2004Y. Ishitani Abstract InN crystals are grown on sapphire substrates using a plasma-assisted MBE system. The carrier concentrations of the samples are 2 × 1018,1 × 1019 cm,3. Optical transmission and reflectance measurements are performed on these samples in the temperature range 5,300 K. The resultant spectra are analysed by theoretical spectra based on the LO-phonon,plasmon coupling scheme for the phonon-related factor and non-parabolic conduction band structure for the electronic transition factor. The observed absorption edge is estimated to originate from a valence band to conduction band transition rather than a defect- or impurity-related transition. It is estimated that InN has a bandgap energy in the range 0.59,0.65 eV. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis, growth and characterization of single crystals of pure and thiourea doped L-glutamic acid hydrochlorideCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2007R. Sathyalakshmi Abstract L(+)Glutamic acid hydrochloride [HOOC (CH2)2CH(NH2) COOH·HCl], a monoamino dicarboxylic acid salt of L-Glutamic acid was synthesized and the synthesis was confirmed by FTIR analysis. Solubility of the material in water was determined. Pure and Thiourea doped L-Glutamic acid hydrochloride crystals were grown by low temperature solution growth using solvent evaporation technique. XRD, UV-Vis-NIR analyses were carried out for both pure and thiourea doped crystals. The crystals were qualitatively analyzed by EDAX analysis and the presence of thiourea was confirmed. The cell parameters of L-Glutamic acid hydrochloride have been determined as a = 5.151 Å, b = 11.79 Å, c = 13.35 Å by X-ray diffraction analysis and it crystallizes in orthorhombic space group P212121. UV-Vis-NIR spectra analysis showed good optical transmission in the entire visible region for both pure and doped crystals. Micro hardness of both pure and doped crystals has been determined using Vickers micro hardness tester. The SHG efficiencies of both pure and doped crystals were determined using Kurtz powder test and pure L-Glutamic acid hydrochloride crystal was found to possess better efficiency than thiourea doped L-Glutamic acid hydrochloride crystals. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Physical properties of Dy and La doped SnO2 thin films prepared by a cost effective vapour deposition techniqueCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2006J. Joseph Abstract Stannous oxide (SnO2) thin film is one of the most widely used n-type transparent semi-conductor films in electronics, electro-optics and solar energy conversion. By achieving controlled non-stoichiometry, we can get good transparency and high electrical conductivity simultaneously in SnO2 thin films. Dy and La doped SnO2 thin films have been prepared by a cost effective vapour deposition technique. The structural, photo-electronic, optical and electrical properties of the doped and undoped films were studied. The results of X-ray Diffraction studies reveals the polycrystalline nature of the films with preferential orientation along the (101), (211) and (301) planes and their average grain size variation for different deposition temperature. Photoconductivity and Photovoltaic studies of the films were also performed. The optical properties of these films were studied by measuring their optical transmission as a function of wavelength. The optical transmission is found to be increased on Dy doping and decreased on La doping. The band gap, refractive index and thickness of the films were calculated from U-V transmittance and Absorption graphs. The optical band gap of undoped film is found to be 4.08 eV, but on doping it shifts to lower energies and then increases on increasing the concentration of both dopants. Its electrical parameters such as sheet resistance, resistivity, mobility, Hall coefficient, and carrier concentration were determined by Four Probe, Van der Pauw and Hall Probe method. On doping with Dy, carrier conversion takes place from n-type to p-type and p-conductivity dominates. On La doping no carrier conversion takes place but resistivity decreases. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Part 1: Kinetics and mechanism of the crystallization processCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2006Oleg D. Linnikov Abstract The kinetics of spontaneous crystallization of sodium chloride from aqueous-ethanol solutions were studied. During the crystallization the electrical conductance and optical transmission of the supersaturated solutions were measured automatically. For monitoring of the total surface of growing potassium chloride crystals at the crystallization the turbidimetric method was used. The growth rate and activation energy were determined. The crystal growth rate was proportional to supersaturation. When the volume fraction of ethanol in solution increased from 14.85 to 29.72%, the activation energy of the growth process did not change and was about 50 kJ· mol -1. Aggregation of the crystals was found. The aggregation kinetics of the crystals may be described approximately by the famous Smoluchowski equation for coagulation of colloidal particles. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Dry film microchips for miniaturised separationsELECTROPHORESIS, Issue 24 2009Rosanne M. Guijt Abstract In this work microfluidic devices were made from the dry film photoresist Ordyl SY330, characterised by optical and electron microscopy and used for electrophoretic separations. A simple and fast microfabrication process was developed for the fabrication of channels that are 50,,m wide and 30,,m in height, requiring only the use of an office laminator, a hot plate, an exposure source and mask and an electric drill to make four microdevices in less than 1,h. The optical properties of the photoresist were studied and the resist showed significant absorbance below 370,nm and 570,630,nm, and had an optical transmission of 80% between 400 and 550,nm. Fluorescence emission over the region of maximum transmission was low allowing these devices to be used for fluorescence detection at 488/512,nm. Electrophoretic separation of APTS and three derivatised sugars was performed in 20,mM phosphate buffer, pH 2.5 with efficiencies of the three sugars of 40,000 plates (2,100,000,plates/m) within 30,s at a field strength of 500,V/cm. The simple fabrication process also allowed microchannels to be easily filled with chromatography particles before sealing, avoiding the challenging task of slurry packing, and the potential of these devices for liquid chromatography was demonstrated by the extraction of fluorescein onto anion exchange particles. [source] Fabrication of Highly Conductive Poly(3,4-ethylenedioxythiophene) Films by Vapor Phase Polymerization and Their Application in Efficient Organic Light-Emitting Diodes,ADVANCED MATERIALS, Issue 17 2007A. Levermore Flexible polymer light-emitting diodes (see photo) are fabricated using highly conductive vapor-phase polymerized poly(3,4-ethylenedioxythiophene) (VPP,PEDOT) as an anode material. The influence of the VPP,PEDOT film thickness and the effects of thermal annealing and oxygen-plasma treatment on conductivity, work function, and optical transmission are explored and used to optimize device performance, resulting ultimately in devices that have efficiencies comparable to those with indium tin oxide anodes. [source] Synthesis and characterization of novel polyimide/SiO2 nanocomposite materials containing phenylphosphine oxide via sol-gel techniqueJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Canan Kizilkaya Abstract In this article, a series of novel polyimide/silica (PI/SiO2) nanocomposite coating materials were prepared from tetraethoxysilane (TEOS), ,-glycidyloxypropyltrimethoxysilane (GOTMS), and polyamic acid (PAA) via sol-gel technique. PAA was prepared by the reaction of 3,3,,4,4,-benzophenone tetracarboxylic dianhydride (BTDA) and bis (3-aminophenyl) phenyphosphine oxide (BAPPO) in N -methyl-2- pyrrolidone (NMP). BAPPO was synthesized hydrogenation of bis (3-nitrophenyl) phenyphosphine oxide (BNPPO) in the presence of Pd/C. The silica content in the hybrid coating materials was varied from 0 to 20 wt %. The molecular structures of the composite materials were analyzed by means of FT-IR and 29Si-NMR spectroscopy techniques. The physical and mechanical properties of the nanocomposites were evaluated by various techniques such as, hardness, contact angle, and optical transmission and tensile tests. These measurements revealed that all the properties of the nanocomposite coatings were improved noticeable, by the addition of sol-gel precursor into the coating formulation. Thermogravimetric analysis showed that the incorporation of sol-gel precursor into the polyimide matrix leads to an enhancement in the thermal stability and also flame resistance properties of the coating material. The surface morphology of the hybrid coating was characterized by scanning electron microscopy (SEM). SEM studies indicated that nanometer-scaled inorganic particles were homogenously dispersed throughout the polyimide matrix © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] How light gets through periodically nanostructured metal films: a role of surface polaritonic crystalsJOURNAL OF MICROSCOPY, Issue 3 2003A. V. Zayats Summary The physical origin of the enhanced optical transmission of periodically structured films related to surface plasmon polaritons is discussed from first principles. The enhancement of transmission through smooth, randomly rough and periodically nanostructured films is considered. Analysis shows that any metal (or dielectric) nanostructured film can exhibit enhanced transmission in certain spectral ranges corresponding to surface plasmon (or phonon) polariton Bloch mode states on a periodic structure. Resonant tunnelling via these states is responsible for the transmission enhancement. The properties of surface polaritonic crystals are analogous to those of photonic crystals and can find numerous applications for scaling down optical devices to nanometric dimensions as well as for designing novel nanostructured materials whose optical properties are determined by surface polariton interaction in a periodic structure. [source] Raman studies and optical properties of some (PbO)x(Bi2O3)0.2(B2O3)0.8,x glassesJOURNAL OF RAMAN SPECTROSCOPY, Issue 9 2008Katerina Kotkova Abstract Five (PbO)x(Bi2O3)0.2(B2O3)0.8,x glasses, where x = 0, 0.2, 0.3, 0.4 and 0.6, were prepared. The dilatometric glass transition temperature (Tg) was found in the region 470 (x = 0), Tg ( °C) , 347 (x = 0.6), and the density (,) varied within 4.57 (x = 0) , , (g/cm3) , 8.31 (x = 0.6). Raman spectra indicated the conversion of BO3 to BO4 entities for low x values but for x > 0.3, namely, for x , 0.6, back-conversion occurred, most probably. From the measurements of the optical transmission on very thin bulk samples, the room temperature optical gap values (Eg) were determined to be in the range 4.03 (x = 0), Eg (eV) , 3.08 (x = 0.6). The temperature (T) dependence of the optical gap (Eg(T)) in the region 300 , T(K) , 600 was examined and approximated by a linear relationship of the form of Eg(T) = Eg(0), ,T, where , × 10,4(eV/K) varied from 5.1 to 6.8. The non-linear refractive index (n2) was estimated from the optical gap values and it was found to correspond to the n2 values calculated from the experimental third-order non-linear optical susceptibility taken from the literature. Copyright © 2008 John Wiley & Sons, Ltd. [source] Aqueous Corrosion of the GeSe4 Chalcogenide Glass: Surface Properties and Corrosion MechanismJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2009Yi-Fan Niu The aqueous corrosion behavior of the GeSe4 glass composition has been studied over time under various conditions (temperature and pH). The evolution of the surface topography by atomic force microscopy and properties such as surface hardness and reduced modulus, as well as the optical transmission in the 1,16 ,m window, have been measured as a function of time spent in the corrosive solution. It was found that even if the glass reacts at room temperature, its optical transparency was barely affected. Nevertheless, the durability of GeSe4 was found to be drastically affected by an increase of both temperature and pH. Furthermore, pure selenium nanoparticles were formed during the corrosion process, and the nature of these nanoparticles,amorphous or crystallized (hexagonal phase),depends on temperature. A reaction mechanism was proposed, and the activation energy of the reaction of corrosion in deionized water (47 kJ/mol) was determined from an original technique that relies on the temporal optical loss variation of a GeSe4 optical fiber placed in water at different temperatures. [source] Stimulated Brillouin scattering and Rayleigh cooperative process in 300 km optical transmissionMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2007Dechao Zhang Abstract The generation of high-order Brillouin Stokes is experimentally demonstrated in 300 km all-Raman transmission with normal Raman pumps and without mirror reflection, and a longest ever fiber laser is implemented at the same time. The OSNRs of the two Brillouin Stokes after 300 km are both higher than 29 dB. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2939,2941, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22899 [source] Polariscopic imaging and vibrational characterization of hybrid films for packagingPACKAGING TECHNOLOGY AND SCIENCE, Issue 6 2008Iari-Gabriel Marino Abstract Polymeric films (low-density polyethylene and oriented polypropylene) for packaging applications coated with organic,inorganic nanocomposite hybrids have been prepared by sol-gel process. Tetraethoxysilane and two different organic phases, polyvinyl alcohol and a diblock copolymer polyethylene-polyethylene glycol were used as precursors. Information about the hydrolysis and polycondensation degrees was obtained by investigating the vibrational features of the coatings by means of attenuated total reflectance-Fourier transform infrared and Raman spectroscopies. Through a new polariscopic imaging technique, the bi-dimensional maps of the optical anisotropy of the samples, both as-prepared and under mechanical strain, were obtained. The maps showed inhomogeneous retardation and nearly flat azimuth distributions. The anisotropy properties of the samples depended mainly on the substrates and were not influenced by the coatings, while the optical transmission was slightly better for the tetraethoxysilane-polyvinyl alcohol sample. Copyright © 2008 John Wiley & Sons, Ltd. [source] HRTEM, Raman and optical study of CdS1,xSex nanocrystals embedded in silicate glassPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 13 2004V. Bellani Abstract We studied CdS1,xSex nanocrystals embedded in a silicate glass by means of complementary techniques like high resolution transmission electron microscopy (HRTEM), micro-Raman spectroscopy and optical transmission and reflectivity. Transmission Electron Microscopy gives complete information on crystallization and size distribution of the nanocrystals wile Raman scattering is particularly useful in the determination of the composition of the nanocrystals for low-concentration or small-crystallite size composite. Having the size distribution and composition of the nanocrystals we have explained the transmission spectra of the studied samples. Optical transmission spectra evidence the quantization of the electronic states of the nanoparticles system with a size distribution described by a Gaussian function. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Determination of the band-gap of MgS and MgS-rich Zn1,xMgxSySe1,y alloys from optical transmission measurementsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2010Ian A. Davidson Abstract As part of our development of an epitaxial lift-off process, utilising a sacrificial magnesium sulphide (MgS) layer, we have developed a MgS-rich ZnMgSSe alloy which provides excellent carrier confinement and resists both oxidation and acid attack. Here the optical transmission of the alloy has been measured and its bandgap determined as a direct transition at 4.19,±,0.04,eV. Its composition has also been determined by X-ray interference (XRI) and comparison with simulations. For a range of alloy samples we obtain compositions of the Zn1,xMgxSySe1,y layers which are (x, y),=,(0.80,±,0.02, 0.645,±,0.025). Using the alloy bandgap and composition we have determined direct bandgap transition energy for MgS by extrapolation. This is found to be 4.78,±,0.14,eV. [source] Metallic nanoparticle array on GaN by microsphere lithographyPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009Giuseppe Y. Mak Abstract The optical characteristics of GaN blue-light (peak wavelength at 440 nm) light-emitting diode (LED) under the effect of localized surface plasmon (LSP) have been studied. Hexagonal arrays of triangular metallic nanoparticles deposited through a self-assembled silica microsphere mask have been fabricated using vertical deposition. By comparing the PL spectra of samples coated with Au, Al and Ag nanoparticles, it is found that Ag nanoparticles offer the most pronounced PL enhancement. The resonance wavelength was determined from optical transmission and verified by theoretical calculations. These results provide a cost-effective solution for improving the efficiency of LEDs. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Study on the formation defect of nano imprinted optical waveguide devices and nano-indentation detectionPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 12 2008Y.-J. Weng Abstract In this study, we try to discuss the formation defects found in the application of air-assisted soft mold UV-cured nano imprint lithography technology in the manufacture of optical waveguide devices, and find a solution. Meanwhile, we try to utilize the nano-indentation technology in the material quality detection for optical waveguide devices. The results tell us that there is a corresponding relationship between the indentation hardness and procedure parameters under nano-meter level depth. For example, the indentation tends to be harder when it is lowly loaded and shallow in depth. Closer it gets to the edge of waveguide's turning, lower the indentation hardness will be. At the same time, different exposal process results in different structural intensity. Therefore, the high structural intensity without forming defects of optical waveguide with less optical loss and better optical transmission. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||||||||