1,721,096 research outputs found
Tellurite Glass Optical Fiber Doped With Pbte Quantum Dots
Full text linkWe produced a PbTe quantum dot core doped optical fiber with tellurite glasses intended to be used in highly nonlinear ultrafast optical devices capable to operate at the optical communication window at 1300 and 1500 nm wavelength region. Attenuation peaks of the optical fiber depends on the heat treatment time as expected for dots growth and covered the whole mid infrared region near 1500 nm. The optical fiber preform was made with the rod-in-tube method and the fiber was produced with a 4 m high Heatway drawing tower. The optical fiber core can be heavily doped because tellurite glasses solubility for PbTe quantum dots is order of magnitude higher than borosilicate and phosphate glasses, for example. In order to match all the requirements for core-clad optical fibers we studied undoped and doped tellurite glasses optical and thermophysical properties as a function of the glass composition. We also followed the growth kinetics of the quantum dots by High Resolution Transmission Electron Microscopy in the bulk glass matrix and the optical fiber.5734124129Borrelli, N.F., Aitken, B.G., Newhouse, M.A., (1995) J. Non-cryst.Sol., p. 185Wise, F.W., (2000) Acc. Chem. Res., 33, p. 773Borrelli, N.F., Smith, D.W., (1994) J. Non-cryst. Sol., 180, p. 25Lipovskii, A., Kolobkova, E.A., Petrikov, V., Kang, I., Olkhovets, A., Krauus, T., Thomas, M., Kycia, S., (1997) Appl. Phys. Lett., 71, p. 3406Reynoso, V.C.S., De Paula, A.M., Cuevas, R.F., Neto, J.A.M., Alves, O.L., Cesar, C.L., Barbosa, L.C., (1995) Elect. Lett., 31 (12), pp. 1013-1014Rodriguez, E., Jimenez, E., Jacob, G.J., Neves, A., Cesar, C.L., Barbosa, L.C., Photonics West 2005, , poster 5734-22Jacob, G.J., Cesar, C.L., Barbosa, L.C., (2002) Physics and Chemistry of Glass, 43 C, pp. 250-253Tudury, G.E., Marquezini, M.V., Ferreira, L.G., Barbosa, L.C., Cesar, C.L., (2000) Phys. Rev. B, 62 (11), p. 7357Cho, S.J., Paek, U.C., Han, W.T., Heo, J., (2001) OFC2001, , ThC4-1 paperJu, S., Kim, Y.H., Han, W.T., (2004) ECOC2004, , Stockholm, Sweden, September 5-9, Th2.3.3 pape
One-dimensional Photonic Crystal For The 1.3-1.5 μm Region
Full text linkMultilayer of PbTe quantum dots embedded in SiO2 were fabricated by alternatively use of Plasma Enhanced Chemical Vapor Deposition and Laser Ablation techniques. The optimal growing parameters for both the SiO2 films and the PbTe quantum dots were obtained. The refractive index and optical absorption of the sample were studied. Multilayer X-ray diffraction patterns were used to estimate the nanoparticles diameter. Morphological properties of the nanostructured material were studied using Transmission Electron Microscopy. Both absorption spectra and X-ray diffraction patterns reveled the nanoparticles are 6-8 nm in diameter, consequently appropriate for developing optical devices in the infra red region. Finally the multilayer was grown inside a Fabry Perot cavity. The transmittance of the one-dimensional photonic crystal was measured.6129Tsunetomo, K., Shunsuke, S., Koyama, T., Tanaka, S., Sasaki, F., Kobayashi, S., Ultrafast nonlinear optical response of CdTe microcrystallite-doped glasses fabricated by laser evaporation (1995) Molecular Crystals and Liquid Crystals Science and Technology Section B, Nonlinear Optics, 13 (1-3), pp. 109-126Gleiter, H., (1989) Prog. Mater. Sci., 33, p. 223Tudury, G.E., Marquezini, M.V., Ferreira, L.G., Barbosa, L.C., Cesar, C.L., Effect of band anisotropy on electronic structure of PbS, PbSe, and PbTe quantum dots (2000) Phys. Rev. B, 62 (11), pp. 7357-7364Rodriguez, E., Jimenez, E., Padilha, L.A., Neves, A.A.R., Jacob, G.J., Cesar, C.L., Barbosa, L.C., SiO2/PbTe quantum dots multilayer production and characterization (2005) Appl. Phys. Lett., 86, pp. 113117-113120Rodriguez, E., Jimenez, E., Cesar, C.L., Barbosa, L.C., 1D photonic band gap silica doped PbTe quantum dot optical device (2005) Glass Technology, 46 (2), pp. 47-49Rodriguez, E., Jimenez, E., Neves, A.A.R., Jacob, G.J., Cesar, C.L., Barbosa, L.C., Fabrication and characterization of PbTe quantum dot multilayers for Photonic Fabry-Perot Devices (2005) Physica E, 26, pp. 361-36
Cdte Quantum-dot Doped Glass For 1 Tbit/s All-opticalswitching
No full textCarrier recombination in CdTe quantum-dots is shown to be faster than 1ps without accumulation in long-lived states. Thermal effects influence absorption for times greater than 1ps. By eliminating those effects we demonstrate all-optical-switching at 1Tbit/s. © 2005 Optical Society of America.Uskov, A.V., O'Reilly, E.P., Manning, R.J., Webb, R.P., Cotter, D., Laemmlin, M., Ledentsov, N.N., Bimberg, D., On Ultrafast Optical Switching Based on Quantum-Dot Semiconductor Optical Amplifiers in Nonlinear Interferometers (2004) IEEE Phot. Technol. Lett., 16, pp. 1265-1267Cotter, D., Burt, M.G., Manning, R.J., Bellow-Band-Gap third-order optical nonlinearity of nanometer size semiconductor crystallites (1992) Phys. Rev. Lett., 68, pp. 1200-1203Padilha, L.A., Neves, A.A.R., Cesar, C.L., Barbosa, L.C., Brito Cruz, C.H., Recombination processes in CdTe quantum -dot-doped glasses (2004) Appl. Phys. Lett., 85, pp. 3256-3258Padilha, L.A., Neves, A.A.R., Rodriguez, E., Cesar, C.L., Barbosa, L.C., Brito Cruz, C.H., Ultrafast optical switching demonstrated with CdTe nanocrystals (2004) App. Phys. Lett., , submitted for publicationRedígolo, M.L., Arellano, W.A., Barbosa, L.C., Brito Cruz, C.H., Cesar, C.L., de Paula, A.M., Temperature dependence of the absorption spectra in CdTe-doped glasses (1999) Semicond. Sci. Tech., 14 (1), pp. 58-6
Persons with disabilities, cancer screening and related factors
Full text linkThe scope of this article is to describe persons with disabilities (PwD) being subjected to cancer screening and the relationship between some social variables and inequalities in performing these tests. A cross-sectional study of cancer screening among PwD was conducted in 2007 with 333 participants interviewed in residence in 4 cities of São Paulo. Variables in the practice of cancer screening, disabilities, gender, age, income of main family breadwinner, ethnicity, use of health services, assistance required, private health insurance, and coverage by the family health program were studied. Frequencies, ?²-test, trend ?² percentages and the Odds Ratios (OR) were used for data analysis. 44% of PwD attended at least one cancer screening at the appropriate time. Persons with visual disabilities and with hearing disabilities were subjected to more screening examinations than those with mobility disabilities and women were attended in screening exams more than men. Persons between the ages of 21 and 60 reported cancer screening more frequently than those between 80 and 97 years of age. The outcomes indicate that PwD have different attitudes toward cancer screening according to the type of disability, gender, and age, which were the variables that directly influenced cancer screening exams<br/
Double Optical Tweezers For 3d Photonic Force Measurements
No full text[No abstract available]12SUPPL. 217601761Ashkin, A., Dziedzic, J.M., Bjorkholm, J.E., Chu, S., (1986) Opt. Lett., 11, p. 288Lock, J.A., (2004) Appl. Opt., 43, p. 2532Mazolli, A., Neto, P.A.M., Nussenzveig, H.M., (2003) Proc. Royal Soc. London Ser. A Math. Phys. Eng. Sci., 459, p. 3021Fontes, A., Neves, A.A.R., Moreira, W.L., De Thomaz, A.A., Barbosa, L.C., De Paula, A.M., Cesar, C.L., (2005) Appl. Phys. Lett., 87. , Art. No. 221109Bohren, C.F., Huffman, D.R., (1983) Absorption and Scattering of Light by Small Particles, , John Wiley & Sons, New YorkNeves, A.A.R., Fontes, A., Padilha, L.A., Rodriguez, E., Brito Cruz, C.H., Barbosa, L.C., Cesar, C.L., (2006) Phys. Rev. Lett., , submitted t
Pbte Quantum Dots In Tellurite Glass Microstructured Optical Fiber
Full text linkPbTe doped tellurite glass photonic optical fiber for non linear application were developed using rod in tube method in a draw tower. We follow the growth kinetics of the quantum dots in the optical fiber by High Resolution Transmission Electron Microscopy giving some results related with the growth kinetic of the same in function of time so much for optical fiber as for the glass bulk. Absorption peak near 1500 nm as observed and it was attributed the optical resonance due PbTe quantum dots in the core fiber.6902Tsunetomo, K., (1995) Nonlinear Opt, 13, p. 109Borrelli, N.F., Smith, D.W., (1994) J. Non-Cryst. Soi, 180, p. 25Lipovskii, A., Kolobkova, E.A., Petrikov, V., Kang, I., Olkhovets, A., Krauus, T., Thomas, M., Kycia, S., (1997) Appl. Phys. Lett, 71, p. 3406Reynoso, V.C.S., de Paula, A.M., Cuevas, R.F., Medeiros Neto, J.A., Alves, O.L., Cesar, C.L., Barbosa, L.C., (1995) Elect. Lett, 31 (12), pp. 1013-1014Rodrigues, E., Jimenez, E., Jacob, G.J., Neves, A.A.A., Cesar, C.L., Barbosa, L.C., (2005) Phisica E, 26, pp. 321-325Jacob, G.J., Cesar, C.L., Barbosa, L.C., Tellurite Glass Doped with PbTe Quantum Dots (2002) Physics and Chemistry of Glass, 43 C, pp. 250-253Jacob, G.J., Rodriguez, E., Barbosa, L.C., Cesar, C.L., Tellurite Glass Optical fiber doped with PbTe Quantum DotsPhotonics West 2005, The International Society for Optical Engineering SPIEEnomoto, Y., Tokuyama, M., Kawasaki, K., (1986) Act. Metall, 34, p. 2139Marqusee, J.A., Ross, J., (1984) J. Chem. Phys, 80, p. 536Lifshitz, E.M., Slyozov, V.V., (1961) J. Phys. Chem. Sol, 19, p. 3
Micro-structured Er 3+-tm 3+ Co-doped Tellurite Fiber For Broadband Optical Amplifier Around 1550nm
Full text linkMicro-structured Er 3+-Tm 3+ co-doped tellurite fiber with three rings of holes was fabricated using a soft glass drawing tower by a stack-and-draw technique. Amplified spontaneous emission (ASE) around 1550nm band were observed when pumped with both, 980nm and 790nm, lasers.6314Russell, P., Photonic crystal fibers (2003) Science, 299, pp. 358-362Knight, J.C., Photonic crystal fibers (2003) Nature, 424, pp. 847-851Kumar, V.V.R.K., George, A.K., Reeves, W.H., Knight, J.C., Russell, P.St.J., Omenetto, F.G., Taylor, A.J., Extruded soft glass photonic crystal fiber for ultrabroad supercontinuum generation (2002) Opt. Exp, 10 (25), pp. 1520-1525Chillcce, E.F., Cordeiro, C.M.B., Barbosa, L.C., Cruz, C.H.B., Er 3+-Tm 3+ co-doped tellurite fibers for broadband optical fiber amplifier around 1550nm band (2006) Opt. Fiber Technol., 12, pp. 185-195Chillcce, E.F., Rodriguez, E., Neves, A.A.R., Moreira, W.C., Cesar, C.L., Barbosa, L.C., Cruz, C.H.B., Tellurite photonic crystal fiber by a stack-and-draw technique (2006) J. Non-cryst. Solids, , accepted to publicationWhite, T.P., McPhedran, R.C., De Sterke, C.M., Botten, L.C., Steel, M.J., Confinement losses in microstructured optical fibers (2001) Opt. Lett, 26 (21), pp. 1660-1663Barbosa, L.C., Cruz, C.H.B., Cesar, C.L., Cordeiro, C.M.B., Chillcce, E.F., Production process of tellurite glass tubes, capillaries and rods Brazilian pending Patent No 018050002734Chillcce, E.F., Cordeiro, C.M.B., Rodriguez, E., Cruz, C.H.B., Cesar, C.L., Barbosa, L.C., Tellurite photonic crystal fiber with Er 3+-Tm 3+ for broadband optical amplifier in 1550nm (2006) Proc. of SPIE, 6116, p. 61160
Influence Of The Growing Parameters On The Size Distribution Of Pbte Nanoparticles Produced By Laser Ablation Under Inert Gas Atmosphere
No full textWe report the fabrication of PbTe quantum dots grown under inert gas (Ar and He) atmosphere by pulsed laser deposition using the second harmonic of a Q-Switched Quantel Nd:YAG laser. For characterization, samples were prepared onto a 40Å carbon film deposited on a copper grid. The influence of background pressure, and number of laser pulses on the size distribution of the PbTe nanoparticles was investigated by transmission electron microscopy using a 200 kV TECNAI G2 F20 electron microscope with 0.27 nm point resolution. The size distribution was obtained by manually outlining the particles from several dozens of low- and high-resolution TEM images. Once digitized and saved in a proper format, the image was processed using the J-image software. Characterizations reveal an increase of the nanoparticle size both with the amount of material deposited (number of laser pulses) and the background pressure. Furthermore, measurements reveal a narrower nanoparticle size distribution by increasing the number of laser pulses or by decreasing the background pressure. HRTEM studies of the influence of different ambient gases on the structural properties of the PbTe nanoparticles are being conducted. © 2012 SPIE.8245The Society of Photo-Optical Instrumentation Engineers (SPIE)Tsunetomo, K., Shunsuke, S., Koyama, T., Tanaka, S., Sasaki, F., Kobayashi, S., Ultrafast nonlinear optical response of CdTe microcrystallite-doped glasses fabricated by laser evaporation (1995) Molecular Crystals and Liquid Crystals Science and Technology Section B, Nonlinear Optics, 13 (1-3), pp. 109-126Gleiter, H., Nanocristalline materials (1989) Prog. Mater. Sci., 33, pp. 223-315Rodriguez, E., Kellermann, G., Craievich, A.F., Jimenez, E., Cesar, C.L., Barbosa, L.C., All-optical switching device for infrared based on PbTe quantum dots (2008) Superlattices and Microstructures, 43 (5-6), pp. 626-634. , DOI 10.1016/j.spmi.2007.07.017, PII S0749603607002352Tudury, G.E., Marquezini, M.V., Ferreira, L.G., Barbosa, L.C., Cesar, C.L., Effect of band anisotropy on electronic structure of PbS, PbSe, and PbTe quantum dots (2000) Physical Review B - Condensed Matter and Materials Physics, 62 (11), pp. 7357-7364. , DOI 10.1103/PhysRevB.62.7357Rodriguez, E., Jimenez, E., Neves, R.A.A., Jacob, J.G., Cesar, C.L., Barbosa, L.C., (2005) Appl. Phys. Lett., 86, pp. 113117-113120Rodriguez, E., Jimenez, E., Neves, A.A.R., Jacob, G.J., Cesar, C.L., Barbosa, L.C., (2005) Physica E, 26, pp. 361-365Afonso, C.N., Gonzalo, J., Serna, R., De Sande, J.C.G., Ricolleau, C., Grigis, C., Gandais, M., Townsend, P.D., Vacuum versus gas environment for the synthesis of nanocomposite films by pulsed-laser deposition (1999) Appl. Phys. A., 69 (SUPPL.), pp. S201-S207Afonso, C.N., Serna, R., Ballesteros, J.M., Petford-Long, A.K., Doole, R.C., (1998) Appl. Surf. Sci., (339), pp. 127-129Rodriguez, E., Jimenez, E., Moya, L., Cesar, C.L., Cardoso, L.P., Barbosa, L.C., Plasma dynamics studies during deposition of thin film PbTe on a glass substrate (2006) Vacuum, 80 (8), pp. 841-849. , DOI 10.1016/j.vacuum.2005.07.005, PII S0042207X05002368Kellermann, G., Rodriguez, E., Jimenez, E., Cesar, C.L., Barbosa, L.C., Craievich, A.F., Structure of PbTe(SiO2)/SiO2 multilayers deposited on Si(111) (2010) J. Appl. Cryst., 43 (3), pp. 385-389Rodriguez, E., Ponce, L., Arronte, M., De Posada, E., Kellerman, G., César, C.L., Barbosa, L.C., Glass doped with semiconductor nanoparticles for optical devices (2009) Proc. SPIE., 7499, p. 74991
Pbte Quantum Dots - Sio2 Multilayers For Optical Devices Produced By Laser Ablation
Full text linkThin films of glass doped with PbTe quantum dots were successfully fabricated. The semiconducting quantum dots were grown by laser ablation of a PbTe target (99.99%) using the second harmonic of a Q-Switched Quantel Nd:YAG laser under high purity argon atmosphere. The glass matrix was fabricated by a plasma chemical vapor deposition method using vapor of tetramethoxysilane (TMOS) as precursor. The QD's and the glass matrix were alternately deposited onto a Si (100) wafer for 60 cycles. Cross-section TEM image clearly showed QD's layer well separated from each other with glass matrix layers. The influence of the ablation time on the size distribution of the quantum dots is studied. HRTEM revealed anisotropy in the size of the QD's: they were about 9nm in the high and 3-5 in diameter. Furthermore HRTEM studies revealed that the QD's basically growth in the (200) and (220) directions. The thickness of the glass matrix layer was about 20 nm. Absorption, photo luminescence and relaxation time of the multilayer were also measured.5734116123Alivisatos, A.P., (1996) Sci., 271, p. 933Warnock, J., Awschalom, D.D., (1985) Phys. Rev. B, 32, p. 5529Borrelli, N.F., May, D.W., Holland, H.J., Smith, D.W., (1987) J. Appl. Phys., 61, p. 399Potter, B.G., Simmons, J.H., (1988) Phys. Rev. B, 37, p. 10838Gleiter, H., (1989) Prog. Mater. Sci., 33, p. 223Tsunetomo, K., Shunsuke, S., Koyama, T., Tanaka, S., Sasaki, F., Kobayashi, S., (1995) Nonlinear Opt., 13, p. 109Reynoso, V.C.S., De Paula, A.M., Cuevas, R.F., Neto, J.A.M., Alves, O.L., Cesar, C.L., Barbosa, L.C., (1995) Electr. Lett., 31 (12), pp. 1013-1015Jacob, G.J., Cesar, C.L., Barbosa, L.C., (2002) Chem. Phys. Glass, 43 C, pp. 250-252Singh, R.K., Narayan, J., (1990) Phys. Rev. B, 41, p. 8843Barnes, J.P., (2002) Nanotechnology, 13, p. 465Tudury, G.E., Marquezini, M.V., Ferreira, L.G., Barbosa, L.C., Cesar, C.L., (2000) Phys. Rev. B, 62 (11), pp. 7357-7364Cesar, C.L., Jacob, G.J., Tudury, G.E., Marquezini, M.V., Barbosa, L.C., (2004) Atti della Fondazione G. Ronchi Journal, (4), pp. 519-528. , Anno LI
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