Physics. Toward organic all-optical switching.

Department of Chemistry, Imperial College, London SW7 2AZ, UK.
Science (Impact Factor: 31.48). 03/2010; 327(5972):1466-7. DOI: 10.1126/science.1188291
Source: PubMed
  • [Show abstract] [Hide abstract]
    ABSTRACT: An all-optical pulse controlled switch/modulator based on evanescent coupling between a polymer slab waveguide and a single mode fiber is demonstrated. Very fast all-optical modulation/switching is achieved via Kerr effect of the nonlinear polymer placed in the evanescent region of the optical fiber. Local refractive index perturbation (Delta n = -1.45612 x 10(-5)) on the thin film leads to 0.374 nW power modulation at the fiber output, which results in a switching efficiency of approximate to 1.5%. (C) 2014 Optical Society of America
    Optics Letters 03/2014; 39(6):1469-72. DOI:10.1364/OL.39.001469 · 3.18 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The goal of this study is to determine the electrically conductivity of the polymers poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate): N-methyl-2-pyrrolidinone (PEDOT: PSS: NMP) and PEDOT: PSS when blended with polyvinyl alcohol (PVA). While the conducting polymers have high conductivity when not blended with PVA, they are brittle and difficult to spin-coat. Thus, the motivation for this study is to develop blends of these two conducting polymers with PVA to produce a material with optimized mechanical properties and that can also be spin-coated. The blends are produced using aqueous preparations of these materials. Mixtures of various weight percentages (wt %) of PEDOT: PSS: NMP and PEDOT: PSS are prepared and spin-coated on glass slides to form thin films. In the blends, the film conductivity increases with increasing content of either PEDOT: PSS: NMP or PEDOT: PSS. For example, 100 wt % of PEDOT: PSS: NMP and 60 wt % of PEDOT: PSS: NMP blended with PVA exhibit conductivities of, respectively, 10 and 4.02 S/cm. In contrast, conductivities of only 0.0525 and 0.000506 S/cm are observed, respectively, for 100 wt % of PEDOT: PSS and 60 wt % of PEDOT: PSS content in the PEDOT: PSS/PVA blends (No NMP). The addition of the NMP enhances the electrical conductivity by two to five orders of magnitude (depending on the amount of PVA in the blend) due to conformational change of PEDOT chains. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
    Journal of Applied Polymer Science 08/2012; 125(4). DOI:10.1002/app.36474 · 1.64 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A novel cuprous(I) cluster Cu4I4L4 (L = (E)-(4-diethylanilino-styryl)pyridine) bearing strong two-photon absorption (TPA) was obtained using a facile assembly method, and the crystal structure has been determined. Quantum chemical calculations using time-dependent density functional theory (TD-DFT) reveals that the combination of the organic ligands with the three-dimensional Cu4I4 core extends the electronic delocalization in the cluster, leading to strong two-photon absorption action. The TPA cross sections (Φσ2) of Cu4I4L4 were enhanced with increasing polarity of solvents, which is quite different from the solvent effects on TPA in the literature. Compared to its free ligand, the cluster Cu4I4L4 exhibits larger peak TPA cross sections in the near-infrared region, longer fluorescence lifetimes, higher quantum yield and photostability, lower cytotoxicity, and brighter two-photon fluorescent (TPF) bioimaging. These integrated advantages make it desirable to be applied as a two-photon fluorescent probe for labeling the nucleic acids in live cells.
    Chemistry of Materials 12/2011; 24(5):954-961. DOI:10.1021/cm2029855 · 8.54 Impact Factor