Tellurite Glass Optical Fiber Doped With Pbte Quantum Dots

We 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

Vector boson Pair Production at Supercolliders; useful approximate helicity amplitudes

We study vector boson pair production at $LHC$ and $SSC$, taking into account the effects generated by the anomalous vector boson and Higgs couplings induced by the operators ${\cal O}_W$ and ${\cal O}_{UW}$, which are the only dim=6 operators preserving $SU(2)_c$. These operators lead to enhanced production of transverse vector bosons, as opposed to the enhanced production of longitudinal gauge bosons, induced in case M_H\gsim 1\ TeV, by dim=4 terms already existing in the Standard Model lagrangian. For vector boson pair masses larger than $1\ TeV$, we establish very simple approximate expressions for the standard as well as the non-standard helicity amplitudes for $q\bar q$ annihilation and vector boson fusion, which accurately describe the physics. These expressions should simplify the experimental search for such interactions. We finally discuss the observability and the disentangling of these interactions.Comment: 22 pages, 6 figures avaible by air mail upon request , (e-mail [email protected] PM/93-26 THES-TP 93/

Unitarity Constraints for New Physics Induced by dim-6 Operators

We compute the helicity amplitudes for boson-boson scattering at high energy due to the operators \O_{B\Phi}, \O_{W\Phi} and \O_{UB}, and we derive the corresponding unitarity bounds. Thus, we provide relations between the couplings of these operators and the corresponding New Physics thresholds, where either unitarity is saturated or new degrees of freedom are excited. We compare the results with those previously obtained for the operators \O_W and \O_{UW} and we discuss their implications for direct and indirect tests at present and future colliders. The present treatment completes the study of the unitarity constraints for all blind bosonic operators.Comment: 41 pages, latex file. PM 94-28 THES-TP 94-0

Unitarity Constraints for Transverse Gauge Bosons at LEP and Supercolliders

Using asymptotic helicity amplitudes for Vector-Vector, Vector-Higgs and Higgs-Higgs scattering, we establish the unitarity constraints on the $SU(2)_c$ conserving and $W_\mu$ depending interactions, which at sufficiently high energies may create strong forces among the transverse vector boson and Higgs states. We then derive upper bounds for the couplings of these interactions, which depend on the high energy scale where unitarity is saturated. If \eg\, unitarity is saturated at 1TeV, then \lambda_W \lsim 0.12 is obtained. The implied relations between the present and future LEP results, and the possible observations of strong effects at supercolliders, are also discussedComment: 11 pages,postscript file of 1 figure appended at the end of the latex file (e-mail [email protected] PM/93-37 THES-TP 93/1

Carbon Nanotube Doped Tellurite Glasses

In the past it was observed that buck ball doped glasses showed enhanced optical nonlinearities. However, carbon nanotubes are much more stable than buck ball and should be a better choice for that purpose. Therefore we decided to investigate the possibility to produce carbon nanotubes doped tellurite glasses and measured their optical nonlinearities. Tellurite glasses already have a larger nonlinearity compared to silica, and other, glasses. We produced TeO 2-ZnO tellurite family glasses doped with multi wall Carbon Nanotube (CNT). The CNTs acquired from Carbolex were vigorously mechanically mixed with the tellurite glass precursors and melted in platinum crucible around 650°C in a controlled atmosphere inside an electrical induction furnace. We used the lowest temperature possible and controlled atmosphere to avoid the CNT oxidation. The glass melt was cast in a stainless steel and thermally treated at 300°C for 5 hours to relieve internal stresses. The samples were than cutted and polished to perform the optical characterization. We measured refractive index and thermo physical properties, such as vitreous transition Tg, crystallization onset Tx and melting Tf temperatures. Raman spectroscopy showed the possible presence of CNTs.6890Iijima, S., (1991) Nature, 354, p. 56http://www.ati.surrey.ac.uk/news/n, onlinearDiMaio, J., Rhyne, S., Yang, Z., Fu, K., Czerw, R., Xu, J., Webster, S., Ballato, J., (2003) Information Sciences, 149, p. 69Aoki, Y., Okubo, S., Kataura, H., Nagasawa, H., Achiba, Y., (2005) Chem. Lett, 34 (4), p. 562Misra, S.K., Watts, P.C.P., Valappil, S.P., Silva, S.R.P., Roy, I., Boccaccini, A.R., (2007) Nanotechnology, 18, p. 07570

Quantum Confinement Effects On The Phonons Of Pbte Quantum Dots In Tellurite Glasses

We present Raman-scattering results for PbTe quantum dots (QDs) in doped telluride glasses which clearly show the confinement effects on the phonon spectra as a function of the quantum-dot size..6892Kraus and F. Wise;Phys. Rev. Lett. 79 (25), 5102-05 (1997)Thoen, E.R., (1998) Appl, Phys. Lett, 73 (15), p. 2149Wise, F., (2000) Ace. Chem. Res, 33, pp. 773-780Tsuda, S., Cruz, C.H.B., (1991) Opt. Lett, 16, p. 1596Nakamura, A., Tokizaki, T., Akiyama, H., Kataoka, T., (1992) J. Lumin, 53, p. 105Ohtsuka, S., Koyama, T., Tsunetomo, K., Nagata, H., Tanaka, S., (1992) Appl. Phys. Lett, 61, p. 2953Tsunetomo, K., Ohtsuka, S., Koyama, T., Tanaka, S., Sasaki, F., Kobayashi, S., (1995) Nonlin. Opt, 13, p. 109Colvin, V.L., Schlamp, M.C., Alivisatos, A.P., (1995) Nature ∼London, 370, p. 354Dabbousi, M., Bawendi, G., Onitsuka, O., Rubner, M.F., (1995) Appl. Phys. Lett, 66, p. 1316Guerreiro, T., Ten, S., Borrelli, N.F., Butty, J., Jabbour, G.E., Peyghambarian, N., (1997) Appl. Phys. Lett, 71, p. 1595Murray, C.B., Kagan, C.R., Bawendi, M.G., (1995) Science, 270, p. 1335Kang, I., Wise, F.W., (1997) J. Opt. Soc. Am. B, 14, p. 1632Reynoso, V.C.S., de Paula, A.M., Cuevas, R.F., Medeiros Neto, J.A., Alves, O.L., Cesar, C.L., Barbosa, L.C., (1995) Electron. Lett, 31, p. 1013G.J.Jacob, C.L.Cesar,L.C.Barbosa, Chem.Phys.Glass 43C (2002)250-252Esch, V., Fluegel, B., Khitrova, G., Gibbs, H.M., Jiajin, X., Kang, K., Koch, S.W., Peyghambarian, N., (1990) Phys. Rev, B42, p. 7450Sercel, P.C., Valhala, K.J., (1990) Phys. Rev, B42, p. 3690Schoenlein, R.W., Mittleman, D.M., Shiang, J.J., Alivisatos, A.P., Shank, C.V., (1993) Phys. Rev. Lett, 70, p. 1014Ekimov, A.I., Hache, F., Schanne-Klein, M.C., Ricard, D., Flytzanis, C., Kudryavtsev, I.A., Yazeva, T.V., Efros, A.L., (1993) J. Opt. Soc. Am, B10, p. 100Norris, D.J., Sacra, A., Bawendi, C.B.M.M.G., (1994) Phys. Rev. Lett, 72, p. 2612de Oliveira, C.R.M., de Paula, A.M., Filho, F.O.P., Neto, J.A.M., Barbosa, L.C., Alves, O.L., Menezes, E.A., Cesar, C.L., (1995) Appl. Phys. Lett, 66, p. 439R. Ruppin and R. Englman, Rep. Prog. Phys. 33, 149 (1970)R. Ruppin, J. Phys. C: 8, 1969 (1975)Thoen, E.R., Steinmeyer, G., Langlois, P., Ippen, E.P., Tudury, G.E., Brito Cruz, C.H., Barbosa, L.C., Cesar, C.L., (1998) Appl. Phys. Lett, 73Krauss, T.D., Wise, F.W., Coherent and Acoustical Phonon in a Semiconductor Quantum DotsPhis (1997) Rev. Lett, 79, pp. 5102-510

A FORTRAN code for γγ→ZZ\gamma \gamma \to Z Z in SM and MSSM

Through the present paper, the code gamgamZZ is presented, which may be used to calculate all possible observables related to the process $\gamma \gamma \to ZZ$, in either the Standard Model (SM), or the minimal sypersymmetric standard model (MSSM) with real parameters.Comment: 13 pages, 7 figures Revised according to the EPJC Referee suggestion

Pbte Quantum Dots In Tellurite Glass Microstructured Optical Fiber

PbTe 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

Scarcity of atrial fibrillation in a traditional African population : a community-based study

Background: In western societies, atrial fibrillation is an increasingly common finding among the elderly. Established risk factors of atrial fibrillation include obesity, diabetes, hypertension, and cardiovascular disease. Atrial fibrillation has almost exclusively been studied in western populations where these risk factors are widely present. Therefore, we studied the epidemiology of atrial fibrillation in a traditional African community. Methods: In rural Ghana, among 924 individuals aged 50 years and older, we recorded electrocardiograms to detect atrial fibrillation. As established risk factors, we documented waist circumference, body mass index (BMI), capillary glucose level, blood pressure, and electrocardiographic myocardial infarction. In addition, we determined circulating levels of interleukin-6 (IL6), a proinflammatory cytokine, and C-reactive protein (CRP), a marker of systemic inflammation. We compared the risk factors with reference data from the USA. Results: Atrial fibrillation was detected in only three cases, equalling 0.3% (95% CI 0.1–1.0%). Waist circumference, BMI, and capillary glucose levels were very low. Hypertension and myocardial infarction were uncommon. Circulating levels of IL6 were similar, but those of CRP were lower compared with the USA. Conclusion: Atrial fibrillation is very scarce in this traditional African community. Its low prevalence compared with western societies can be explained by the rareness of its established risk factors, which are closely related to lifestyle, and by possible unmeasured differences in other risk factors or genetic factors.Wetensch. publicati

Birefringence of interferential mirrors at normal incidence Experimental and computational study

In this paper we present a review of the existing data on interferential mirror birefringence. We also report new measurements of two sets of mirrors that confirm that mirror phase retardation per reflection decreases when mirror reflectivity increases. We finally developed a computational code to calculate the expected phase retardation per reflection as a function of the total number of layers constituting the mirror. Different cases have been studied and we have compared computational results with the trend of the experimental data. Our study indicates that the origin of the mirror intrinsic birefringence can be ascribed to the reflecting layers close to the substrate.Comment: To be published in Applied Physics