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Femtosecond laser waveguide micromachining of PMMA films with azoaromatic chromophores

MENDONCA, Cleber Renato; CERAMI, L. R.; SHIH, T.; TILGHMAN, R. W.; BALDACCHINI, T.; MAZUR, E.
Fonte: OPTICAL SOC AMER Publicador: OPTICAL SOC AMER
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
470.50086%
We report on the femtosecond-laser micromachining of poly(methyl methacrylate) (PMMA) films doped with nonlinear azoaromatic chromophores: Disperse Red 1, Disperse Red 13 and Disperse Orange 3. We study the conditions for controlling chromophore degradation during the micromachining of PMMA doped with each chromophore. Furthermore, we successfully used fs-micromachining to fabricate optical waveguides within a bulk sample of PMMA doped with these azochromophores. (c) 2008 Optical Society of America.

Combination of guided mode and photometric optical metrology methods for precise determination of refractive index dispersion: application to polymer blend and ceramic thin films for gas sensors

Wood, Thomas; Le Rouzo, Judikaël; Flory, François; Coudray, Paul; Mastelaro, Valmor Roberto; Pelissari, Pedro; Zilio, Sérgio Carlos
Fonte: International Society for Optical Engineering - SPIE; Bellingham Publicador: International Society for Optical Engineering - SPIE; Bellingham
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
476.52504%
Two optical techniques, m-lines and spectroscopic ellipsometry, are compared for their suitability for obtaining the wavelength and the temperature dispersion of the refractive index of thin-film layers used in gas detector devices. Two types of materials that are often integrated into gas sensors are studied: a polymer organic-inorganic blend deposited by spin coating typically used in near-infrared waveguides and the ceramic semiconductor SrTi1-xFexO3 (strontium titanate) doped with iron at concentrations x = 0.075 and 0.1 deposited by electron beam deposition. The refractive index dispersion obtained by m-lines and ellipsometry is compared, and the differences between the measured parameters for the two materials are discussed. The chromatic dispersion will be represented by a three-term Cauchy law. An intuitive method for verifying the measured indices using an integrating sphere and reflexion coefficient modeling techniques are also demonstrated. Thermo-optic coefficients in the order of -1 × 10-4/K for both materials are reported, and very low chromatic dispersions are also measured, thanks to the high sensitivity of the m-lines technique. The uniaxial anisotropic properties of the polymerblend films are measured and discussed in the case of the semiconductor films.; ANR; CAPES/COFECUB

Real-time optical monitoring of the dip coating process

Michels, A. F.; Menegotto, T.; Grieneisen, H. P.; Santilli, C. V.; Pulcinelli, S. H.; Horowitz, F.; Marcano, A.; Paz, J. L.
Fonte: Spie - Int Soc Optical Engineering Publicador: Spie - Int Soc Optical Engineering
Tipo: Conferência ou Objeto de Conferência Formato: 529-534
ENG
Relevância na Pesquisa
468.07926%
A significant part of film production by the coating industry is based on wet bench processes, where better understanding of their temporal dynamics could facilitate control and optimization. In this work, in situ laser interferometry is applied to study properties of flowing liquids and quantitatively monitor the dip coating batch process. Two oil standards Newtonian, non-volatile, with constant refractive indices and distinct flow properties - were measured under several withdrawing speeds. The dynamics of film physical thickness then depends on time as t(-1/2), and flow characterization becomes possible with high precision (linear slope uncertainty of +/-0.04%). Resulting kinematic viscosities for OP60 and OP400 are 1,17 +/- 0,03. St and 9,9 +/- 0,2 St, respectively. These results agree with nominal values, as provided by the manufacturer. For more complex films (a multi-component sol-gel Zirconyl Chloride aqueous solution) with a varying refractive index, through a direct polarimetric measurement, allowing also determination of the temporal evolution of physical thickness (uncertainty of +/- 0,007 microns) is also determined during dip coating.

Structural transition of ZnO thin films produced by RF magnetron sputtering at low temperatures

Rosa, A. M.; Da Silva, E. P.; Chaves, M.; Trino, L. D.; Lisboa Filho, Paulo Noronha; Da Silva, T. F.; Durrant, S. F.; Bortoleto, J. R R
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 3143-3148
ENG
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487.61152%
Zinc oxide (ZnO) thin films were prepared using reactive radio-frequency magnetron sputtering of a pure metallic zinc target onto glass substrates. The evolution of the surface morphology and the optical properties of the films were studied as a function of the substrate temperature, which was varied from 50 to 250 C. The surface topography of the samples was examined using atomic force microscopy (AFM), and their optical properties were studied via transmittance measurements in the UV-Vis-NIR region. DRX and AFM analyses showed that the surface morphology undergoes a structural transition at substrate temperatures of around 150 C. Actually, at 50 C the formation of small grains was observed while at 250 C the grains observed were larger and had more irregular shapes. The optical gap remained constant at ∼3.3 eV for all films. In the visible region, the average optical transmittance was 80 %. From these results, one can conclude that the morphological properties of the ZnO thin films were more greatly affected by the substrate temperature, due to mis-orientation of polycrystalline grains, than were the optical properties. © 2013 Springer Science+Business Media New York.

Effect of y-radiation on the Conduction Mechanism of Thermal Vacuum Deposited Copper Phthalocyanine Thin Films

Arshak, Arousian; Zleetni, S.M.; Arshak, Khalil; Harris, John A.
Fonte: IEEE Computer Society Publicador: IEEE Computer Society
Tipo: info:eu-repo/semantics/conferenceObject; all_ul_research; ul_published_reviewed; none
ENG
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481.1262%
peer-reviewed; The dosimetry properties of thermally evaporated Copper Phthalocyanine (CuPc) thin films were investigated. The conduction mechanism of the asdeposited films was found to be space-charge-limited and their relative permittivity was within the range reported by others [l, 2, 3, 41. The Poole-Frenkel effect became more dominant for the irradiated samples and they displayed large increase in permittivity and colour centre density, although the energies of their optical band gap and trapping levels did not change. The observed linear relationship between the absorbance at 615 nrn and the y-radiation doses validated the use of CuPc as an optical sensor dosimeter especially for low radiation doses. Samples showed a higher radiation tolerance after being annealed for one hour at a temperature of only 323 K. Annealing also restored their initial electrical and optical properties.

Photoluminescence in Er-doped Ge-As-Se chalcogenide thin films

Yan, Kunlun; Wang, Rongping; Vu, Khu; Madden, Steve; Belay, Kidane; Elliman, Robert; Luther-Davies, Barry
Fonte: Optical Society of America Publicador: Optical Society of America
Tipo: Artigo de Revista Científica Formato: 8 pages
Relevância na Pesquisa
474.7695%
We report the properties of thermally evaporated Ge11.5As24Se64.5 chalcogenide films ion implanted at energies of 2.25MeV with Erbium at concentrations up to 0.4 mol%. The effect of post implant annealing on the refractive index of the films and on the 4I13/2→4I15/2 Er transition was studied. Photoluminescence was found to increase significantly and a lifetime of 1.35 ms was obtained in films annealed at 180°C. Different apparent lifetimes for the 4I13/2→4I15/2 transition were obtained for 980nm and 1470nm pumps and the origins of this phenomenon are discussed.; This research was conducted by the Australian Research Council Centre of Excellence for Ultrahigh bandwidth Devices for Optical Systems (project number CE110001018).

Speckle interferometric technique to assess soap films

??ngel Toro, Luciano; Bolognini, N??stor Alberto; Tebaldi, Myrian Cristina; Trivi, Marcelo Ricardo
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: article; Art??culo; publishedVersion
ENG
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469.3725%
An speckle interferometric technique to monitor the thinning process of vertical soap film before the film rupture is presented -- The interferometric arrangement consists in a double aperture pupil optical system which images an input diffuser -- In a first step, a reference specklegram is stored in the computer buffer memory -- Afterwards, the soap film is located in front of one pupil aperture, an uniform displacement of the diffuser is produced and a new speckle pattern is stored -- The soap film status is characterized in terms of the changes that this dynamic phase object introduces in the correlation fringes obtained by applying a FFT algorithm to the resulting summed specklegram. This procedure is done in real time as far as the soap film evolves in the successive status -- It is experimentally demonstrated that the soap film during drawing acts as a variable wedge -- The correlation fringes behavior becomes an important tool to establish the wedge shaped soap film angle and the thickness variations 2003 Elsevier B.V. All rights reserved; CONICET, CICPBA, Fundaci on Antorchas, Faculty of Engineering of the National University of La Plata (Argentina) and the financial support of ICTP-TRIAL Programm,Trieste, Italia.

Prism coupler and microscopic investigations of DNA films

Samoc, Anna; Galewski, Zbigniew; Samoc, Marek; Grote, James G
Fonte: SPIE - The International Society for Optical Engineering Publicador: SPIE - The International Society for Optical Engineering
Tipo: Parte de Livro
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481.1262%
DNA is a polyelectrolyte capable of forming thin films with interesting optical properties. We investigated refractive indices and optical anisotropy of films of the native, sodium ion-based DNA (Na-DNA) and DNA bearing the cetyltrimethylammonium ion (DNA

Nonlinear Photonic Crystals in Chalcogenide Films

Grillet, Christian; Freeman, Darren; Luther-Davies, Barry; Madden, Steve; Smith, Cameron L C; Magi, Eric; McPhedran, Ross; Moss, David J; Steel, Michael J; Eggleton, Benjamin J
Fonte: SPIE - The International Society for Optical Engineering Publicador: SPIE - The International Society for Optical Engineering
Tipo: Conference paper
Relevância na Pesquisa
468.07926%
All optical switching devices based on kerr-effect, where light switches light, are enjoying renewed interest. The dream of ultra compact devices operating at very low power and integrable on a chip is entering the realm of reality thanks to the advent of

Stoichiometric Low Loss Tellurium Oxide Thin Films for Photonic Applications

Vu, Khu; Madden, Steve; Luther-Davies, Barry; Bulla, Douglas
Fonte: Institute of Electrical and Electronics Engineers (IEEE Inc) Publicador: Institute of Electrical and Electronics Engineers (IEEE Inc)
Tipo: Conference paper
Relevância na Pesquisa
481.4689%
Stoichiometric low loss Tellurium Oxide, TeO2, films have been produced by reactive RF sputtering. TeO2 films with propagation loss below 0.1dB/cm at 1550nm have been achieved in as deposited films.

Nonlinear optical susceptibility of multicomponent tellurite thin film glasses

Muñoz-Martín, David; Fernández Martínez, Héctor; Fernández Navarro, José María; Gonzalo de los Reyes, José; Solís Céspedes, Javier; García Fierro, José Luis; Domingo, Concepción; García-Ramos, José Vicente
Fonte: American Institute of Physics Publicador: American Institute of Physics
Tipo: Artículo Formato: 135495 bytes; application/pdf
ENG
Relevância na Pesquisa
480.5871%
5 pags.; 3 figs.; 2 tabs.; Tellurite (TeO2–TiO2–Nb2O5) thin film glasses have been produced by pulsed laser deposition. The dispersion of the real and imaginary parts of the linear refractive index has been measured in the range from 300 to 1700 nm. Films present high refractive index (n=2.01) and reduced absorption (k<10−4) at =1500 nm. The nonlinear third order optical susceptibility (|(3)|) has been determined at four different wavelengths (600, 800, 1200, and 1500 nm). The out-of-resonance |(3)| values (~10−12 esu) are found to be ten times higher than those of the bulk glass and 102 times higher than that of silica. Compositional and structural analysis reveals an increase of both the Ti atomic content and the fraction of nonbridging oxygen bonds in the deposited films. Both factors lead to a higher hyperpolarizability of the film constituents that is proposed to be responsible for the high |(3)| value of the films.; The authors acknowledge the financial support of the Spanish Ministry of Education and Science (Project Nos. MAT2005-06508-C02-01 and TEC2005-00074/MIC). D.Munoz-Martin and H. Fernandez acknowledge grants from CSIC–JAE and Spanish Ministry of Education and Science– FPU programmes, respectively.; Peer reviewed

Optically transparent IR reflective heat mirror films of ZNS-AG-ZNS

Smith, Bruce W.
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
486.46242%
Optically transparent heat mirror films, reflective in the infrared, have been produced based on a dielectric - metal - dielectric design using zinc sulfide and silver coatings. Filters exhibit 87% peak transmission in the visible region, while reflecting 80%. in the infrared. Thermal testing indicated the that the layer filters were unstable to treatments above 300 F. Incorporation of thin barrier coatings of magnesium fluoride between the silver and zinc sulfide lavers produced filters with thermal stability to 700 F while retaining optical characteristics of the three laver svstem. These optical and thermal properties offer possible application for the heat mirror films in tungsten source efficiency improvement applications.

Optical, electrical, and structural properties of sputtered aluminum alloy thin films with copper, titanium and chromium additions

Barron, Lance; Neidrich, Jason; Kurinec, Santosh
Fonte: Elsevier - Thin Solid Films Publicador: Elsevier - Thin Solid Films
Tipo: Artigo de Revista Científica
EN_US
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481.4689%
Aluminum alloys containing copper, chromium, and titanium were sputter deposited with the goal of maintaining the high bulk reflectance of aluminum while providing surface topography more suited for optical applications. Films were deposited at room temperature with no additional thermal processing. Results show that copper solute addition generates films that maintain much of the bulk reflectance of pure aluminum while refining surface morphology to create a more specular surface consisting of smaller, more uniform grains. X-ray diffraction studies revealed that copper addition into the aluminum lattice caused both a reduction in the preferred orientation of the film and change in the lattice parameter. Copper concentrations of 1.0% at. and above led to spatial variation in copper content within the films. The addition of titanium and chromium to Al-1.0%Cu films caused further microstructure refinement. Al-2.0%Ti-1.0%Cu and Al-2.0%Cr-1.0%Cu exhibited reflectivity spectra that differ significantly in both inter- and intraband absorption from that of pure aluminum. A dielectric function model combining a surface effective medium and a bulk Lorentz–Drude layer was applied to all alloy films to understand the observed reflectivity. Excellent agreement has been shown between the measured resistivity values and those obtained from the Drude model.; RIT community members may access full-text via RIT Libraries licensed databases: http://library.rit.edu/databases/

Low-loss Waveguides in Ultrafast Laser-deposited As2S3 Chalcogenide Films

Zakery, A.; Ruan, Yinlan; Rode, Andrei V; Samoc, Marek; Luther-Davies, Barry
Fonte: Optical Society of America Publicador: Optical Society of America
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
465.07746%
Ultrafast pulsed laser deposition was used to successfully deposit atomically smooth 5-μm-thick As2S3 films. The as-deposited films were photosensitive at wavelengths close to the band edge (∼520 nm), and waveguides could be directly patterned into the

Electric Field Induced Second Harmonic Generation in Vacuum Evaporated Disperse Red 1 films

Taunaumang, H; Herman, N/A; Tjia, M O; Samoc, Marek
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
465.07746%
We have observed the electric field induced second harmonic (EFISH) generation effect on vacuum deposited Disperse Red 1 (DR1) films using corona poling. There is no second harmonic generation (SHG) signal in the absence of the corona. Room temperature corona charging results in an SHG signal which appears and disappears almost instantaneously upon turning on and turning off the corona field respectively. Combined with earlier spectroscopic studies on molecular organization in vacuum deposited DR1 thin film which suggested vertical orientation of most of the molecules, these results clearly indicate that the DR1 molecules in the film are most likely aligned in antiparallel arrangement. The EFISH effect as well as its fast responses to the on-off operation of corona field and the reduction of the SHG signal at elevated film temperature are explained in terms of effective dc field induced polarization effect on the molecules due to third-order nonlinearity of DR1.

Ultrafast pulsed laser deposition of chalcogenide glass films for low-loss optical waveguides

Luther-Davies, Barry; Kolev, Vesselin Z; Lederer, Maximilian; Ruan, Yinlan; Samoc, Marek; Jarvis, Ruth; Rode, Andrei V; Giesekus, J; Du, K-M; Duering, M.
Fonte: Materials Research Society Publicador: Materials Research Society
Tipo: Conference paper
Relevância na Pesquisa
488.54297%
Ultra-fast pulsed laser deposition using high-repetition-rate short-pulse lasers has been shown to provide high optical quality, super smooth thin films free of scattering centres. The optimized process conditions require short ps or sub-ps pulses with repetition rate in the range 1-100 MHz, depending on the target material. Ultra-fast pulsed laser deposition was used to successfully deposit atomicaliy-smooth, Smicron thick As2S3 films. The as-deposited films were photosensitive at wavelengths close to the band edge (≈520 nm) and waveguides could be directly patterned into them by photo-darkening using an Argon ion or frequency doubled Nd:YAG laser. The linear and nonlinear optical properties of the films were measured as well as the photosensitivity of the material. The optical losses in photo-darkened waveguides were <0.2 dB/cm at wavelengths beyond 1200nm and <0.1 dB/cm in as-deposited films. The third order nonlinearity, n2,As2S3, was measured using both four-wave mixing and the z-scan technique and varied with wavelength from 100 to 200 times fused silica (n2,Silica ≈3×10-16 cm2/W) between 1100nm and 1100nm with low nonlinear absorption. Encouraged by the Ultrafast laser deposition results, we have built a new specialized mode-locked picosecond laser system for deposition of optical films and for laser formation of nanoclusters. The newly developed "state of the art" powerful Nd:YVO laser can operate over a wide range of wavelengths...

Optical properties of an ormosil system comprising methyl- and phenyl-substituted silica

Atkins, Graham; Krolikowska, Maryla; Samoc, Anna
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
472.14133%
We report an organically modified silica (ormosil) system in which the refractive index can be varied from 1.40 to 1.55 by modifying the silica backbone with phenyl and methyl groups, which increase and decrease the refractive index, respectively. By changing the quantities of the phenyl- and methyl-modified precursors in the sol-gel mixture, the refractive index can be varied while keeping the organic fraction of the material constant. Crack-free, dried films up to 15-μm thick have been coated onto silicon and glass substrates, with potential application to optical waveguides for planar integrated circuits. The contributions of SiO-H and C-H absorptions to the attenuation in the communications windows are discussed, along with factors affecting the homogeneity and cracking tendency of the ormosils.

Heavy-ion elastic-recoil detection ananlysis of doped-silica films for integrated photonics

Dall (previously Weijers), Tessica; Gaff, K; Timmers, Heiko; Ophel, T; Elliman, Robert
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
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477.53383%
Photosensitive Ge- and Sn-doped silica films are being developed for integrated photonics applications. Such films can be deposited by plasma assisted deposition techniques and their initial refractive index and photosensitivity are determined by the Ge(Sn):Si:O stoichiometry. The presence of H in the films is detrimental to their performance because it causes optical absorption in the 1.3-1.5 μm wavelength range of interest for telecommunications. Characterization of the films therefore requires accurate determination of the film composition, including the presence of H. Heavy-ion elastic-recoil detection (ERD) is shown to provide such information in a single measurement.

Optical Vortices and Vortex Solitons

Kivshar, Yuri
Fonte: SPIE - The International Society for Optical Engineering Publicador: SPIE - The International Society for Optical Engineering
Tipo: Conference paper
Relevância na Pesquisa
464.2405%
Optical vortices are phase singularities in electromagnetic waves that constitute a unique and fascinating class of phenomena within the context of the physics of light. We present a brief overview of the recent advances in the study of optical vortices propagating in nonlinear media. We demonstrate that self-focusing nonlinearity leads, in general, to the azimuthal instability of a vortex-carrying beam, but it can support novel types of stable (or quasi-stable) self-trapped beams carrying nonzero angular momentum, such as vortex solitons, necklace beams, and soliton clusters. We also describe the properties of the discrete vortex solitons in periodic photonic lattices.

Low-loss Silica-based Optical Film Waveguides Deposited by Helicon-activated Reactive Evaporation

Bulla, Douglas; Li, Wei; Charles, Christine; Boswell, Roderick; Ankiewicz, Adrian; Love, John
Fonte: Institute of Electrical and Electronics Engineers (IEEE Inc) Publicador: Institute of Electrical and Electronics Engineers (IEEE Inc)
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
472.14133%
Planar silica-based optical waveguides have been deposited by a plasma helicon-activated reactive evaporation system, at a low temperature and with reduced hydrogen contamination, on thermally oxidized silicon wafers. The transmission loss of the rib waveguides, formed on the deposited films by etching with hydrofluoric acid, is determined to be lower than 0.1 and 0.7 dB/cm at wavelengths of 1310 and 1510 nm, respectively, for TE polarization. The influence of substrate leakage on propagation loss is determined numerically and compared with experimental results for TE and TM polarizations. The presence of the OH vibrational overtone band in the fabricated waveguides, at a wavelength of around 1385 nm, is discussed in terms of the waveguide structure.