A. F. Garito

University of Pennsylvania, Philadelphia, PA, United States

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Publications (227)573.07 Total impact

  • Masahiro Hosoda · Tatsuo Wada · Anthony F. Garito · Hiroyuki Sasabe
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    ABSTRACT: The third-order nonlinear optical susceptibilities χ(3)1111(-3ω; ω, ω, ω) of macrocyclic compounds such as phthalocyanines and porphyrins are determined for the vacuum deposited and spin coated thin films by optical third-harmonic generation measurements at a wavelength of 1907 nm. The enhancements of the χ(3) values are discussed in terms of the central metal substitution, molecular stacking, extended ring size and number of χ-electrons. We firstly describe the results of extended porphyrin systems with 26 delocalized π-electrons.
    No preview · Article · Jan 2011 · MRS Online Proceeding Library
  • A. F. Garito · J. R. Heflin · K. Y. Wong · O. Zamani-Khamiri
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    ABSTRACT: Using a recently developed many-electron theory of second and third order nonlinear optical susceptibilities, microscopic descriptions of γxxxx(-3ω;ω,ω,ω) are presented for two conformations of polyenes. The importance of electron correlations and the effects of variation in conformation and chain length are discussed.
    No preview · Article · Jan 2011 · MRS Online Proceeding Library
  • Masahiko Hara · Anthony F. Garito · Hiroyuki Sasabe
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    ABSTRACT: Application of molecular beam epitaxy (MBE) and scanning tunneling microscopy (STM), especially for organic molecular systems, has been drawing our attention as a new approach to realizing novel material structures with low dimensionality, which are expected to exhibit important electronic and photonic properties. The following is an outline of our work in progress, including an overview of “nanoscopic” molecular engineering. Future possibilities of fabrication, modification and characterization for organic low-dimensional materials are reviewed with the new concept embraced by “nanoscopic” science and technology.
    No preview · Article · Jan 2011 · MRS Online Proceeding Library
  • A. J. Heeger · A. F. Garito
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    ABSTRACT: The class of solids known as organic charge transfer salts has received considerable attention in recent years. This interest arises from the novelty of the systems as well as from the fact that the flat planar molecules involved lead to anisotropic structures and therefore to pseudo one-dimensional electronic properties. The existence of real physical systems1–3 which have the properties of one-dimensional metals is particularly important because of the exciting possibilities associated with the one-dimensional electron gas.4–10 The pseudo one-dimensionality of the electronic properties of tetrathiofulvalinium tetracyanoquinodimethan (TTF-TCNQ) has been established experimentally by a variety of measurements.3,11–15 As a highly conducting organic metal which remains metallic to relatively low temperatures,11, 15, 16 this system is at the focus of work directed toward understanding the nature of the metallic state in pseudo one-dimensional conductors. More generally, the existence of a class of materials made up of organic molecules as fundamental units allows the possibility of utilizing the flexibility of organic chemistry to design and synthesize molecules with particular characteristics with the intent of achieving a desired bulk solid state property.
    No preview · Chapter · Dec 2007
  • A. R. McGhie · P. J. Nigrey · F. G. Yamagishi · A. F. Garito

    No preview · Article · Dec 2006 · Annals of the New York Academy of Sciences
  • Aydin Yeniay · Renyuan Gao · Kazuya Takayama · Renfeng Gao · Anthony F. Garito
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    ABSTRACT: Single-mode perfluoropolymer waveguide structures exhibiting a polarization-independent ultra low loss of <0.05 dB/cm at 1310 nm and <0.07 dB/cm at 1550 nm with a Δn of 1.6% have been fabricated for the first time. These new low-loss structures indicate relatively high-power-handling reliability at 1310 and 1550 nm. Based on this, a highly efficient arrayed-waveguide grating multi-demultiplexer with a crosstalk of 30±2 dB and an insertion loss of 2.8±0.3 dB is realized.
    No preview · Article · Feb 2004 · Journal of Lightwave Technology
  • Charles J. Horner · Anthony F. Garito
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    ABSTRACT: A procedure for the preparation of a novel class of nitroaniline substituted diacetylene alcohols is reported. The polymerization behavior of one member of this class, 6-(4-nitro-2-trifluoromethylanilino)-2,4-hexadiyn-1-ol (11a), has been studied using X-ray irradiation.
    No preview · Article · Mar 2003 · Die Makromolekulare Chemie

  • No preview · Article · Mar 2003 · Die Makromolekulare Chemie
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    ABSTRACT: A new class of nitroaniline derivatives of diacetylene monomers was synthesized for the study of the nonlinear optical properties of their solid state polymers. Several members provide further examples of solid state polymerization by thermal annealing.
    No preview · Article · Mar 2003 · Die Makromolekulare Chemie
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    ABSTRACT: The solid state polymerization of the disubstituted diacetylene 1,6-bis(2,4-dinitrophenoxy)-2,4-hexadiyne by thermal annealing at 130°C to yield high quality polymer single crystals is reported. This compound is unique in that it polymerizes by thermal annealing but not under ordinary x-ray conditions, thus allowing determination of the crystal structures of both the monomer and polymer by x-ray diffraction. The conditions for solid state polymerization and the structural changes during polymerization were investigated. In addition, the kinetics of polymerization were studied by differential scanning calorimetry. An induction period with activation energy EA(slow) = 139,7 ± 3 kJ/mol (33,4 ± 0,7 kcal/mol) is followed by a rapid polymerization regime with activation energy EA(fast) = 132,2 ± 6 kJ/mol (31,6 ± 1,5 kcal/mol) during which first order kinetics are obeyed. The total heat of polymerization is − ΔHp = 134,7 ± 6 kJ/mol (32,2 ± 1,5 kcal/mol). After polymerization, a disordering phase change takes place with continued isothermal annealing which becomes clearly evident at isothermal annealing temperatures higher than 130°C.
    No preview · Article · Mar 2003 · Die Makromolekulare Chemie
  • John E. Sohn · Anthony F. Garito · Kirit N. Desai · Ram S. Narang · Mark Kuzyk

    No preview · Article · Mar 2003 · Die Makromolekulare Chemie
  • Charles J. Horner · Anthony F. Garito · Kirit N. Desai
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    ABSTRACT: Several new classes of asymmetric diacetylene monomers of the type O2NArNHCH2CCCCCH2R have been synthesized from nitroaniline diacetylene alcohols. The solid state polymerization behavior of several members of these classes has been examined.
    No preview · Article · Mar 2003 · Die Makromolekulare Chemie
  • A. Yeniay · R. Gao · K. Takayama · A.F. Garito
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    ABSTRACT: Perfluoropolymer waveguide structures exhibiting polarization independent ultra low loss of
    No preview · Conference Paper · Jan 2003
  • Renyuan Gao · Renfeng Gao · K. Takayama · A. Yeniay · A.F. Garito
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    ABSTRACT: A 3dB insertion loss 16 16 channel arrayed-waveguide grating (AWG) multi/demultiplexer has been realized based on low absorption loss (<0.001dB/cm) perfluorinated polymers. A temperature dependence of -0.5pm/C was achieved by a novel superstrate tuning technique.
    No preview · Conference Paper · Oct 2002
  • Renyuan Gao · Robert A. Norwood · C. C. Teng · Anthony F. Garito
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    ABSTRACT: The optical properties and characteristics of rare earth- doped polymers have been studied to evaluate their viability for use in optical amplifiers. Rare earth ions are encapsulated in organic, covalently bonded chromophores. The optical properties of various rare earth chromophores doped into polymers are measured and calculated and are then used in numerical simulations of amplifiers and lasers. The result provide an estimate of their potential device performance and establish the fundamental bases for applications in photonics. Owing to their distinct advantages, such as chromophore energy transfer effects, high rare earth ion concentrations, shielding of the ion form high energy vibrations of the host, enhanced optical transition moments and controllable decay rates and branching ratios, rare earth-doped polymers are found to be promising candidates for various device applications. Numerical simulations for samarium and europium doped polymers indicate that gains about 10 dB and greater are achievable in relatively short polymer optical fiber and waveguide amplifiers. Studies of the dependence of metastable state lifetime of rare earth doped polymer systems on doping concentrations reveal that rare earth chromophores dissociation occurs at low concentrations. These results are used to optimize the parameters of our rare earth doped polymer optical waveguide amplifiers.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
    No preview · Article · May 2000
  • Renyuan Gao · Robert A. Norwood · C. C. Teng · Anthony F. Garito
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    ABSTRACT: The optical properties and characteristics of rare earth- doped polymers have been studied to evaluate their viability for use in optical amplifiers. Rare earth ions are encapsulated in organic, covalently bonded chromophores. The optical properties of various rare earth chromophores doped into polymers are measured and calculated and are then used in numerical simulations of amplifiers and lasers. The result provide an estimate of their potential device performance and establish the fundamental bases for applications in photonics. Owing to their distinct advantages, such as chromophore energy transfer effects, high rare earth ion concentrations, shielding of the ion form high energy vibrations of the host, enhanced optical transition moments and controllable decay rates and branching ratios, rare earth-doped polymers are found to be promising candidates for various device applications. Numerical simulations for samarium and europium doped polymers indicate that gains about 10 dB and greater are achievable in relatively short polymer optical fiber and waveguide amplifiers. Studies of the dependence of metastable state lifetime of rare earth doped polymer systems on doping concentrations reveal that rare earth chromophores dissociation occurs at low concentrations. These results are used to optimize the parameters of our rare earth doped polymer optical waveguide amplifiers.
    No preview · Article · May 2000 · Proceedings of SPIE - The International Society for Optical Engineering
  • Renyuan Gao · A.F. Garito

    No preview · Conference Paper · Sep 1999
  • Renyuan Gao · Christopher Koeppen · Guoqi Zheng · Anthony F. Garito
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    ABSTRACT: The observed dissociation of tetrakis rare-earth chromophores in rare-earth-doped organic polymers is reported, and a time-resolved spectroscopic technique is presented to determine quantitatively the fractional concentrations of different chromophore species in various solvents. Based on this technique, the equilibrium constants of tetrakis rare-earth chromophores in rare-earth-doped polymers are determined. Thus, the equilibrium constants for tetrakis rare-earth compounds of benzoyltrifluoroacetonate (BTF), for example, Sm(BTF)(4)P and Eu(BTF)(4)P in methyl methacrylate monomer, are K = 4.7 ? 0.5 x 10(-4) M and K = 1.2 ? 0.5 x 10(-4) M, respectively. In contrast, the tetrakis rare-earth compounds of hexafluoroacetylacetonate (HFA), for example, Sm(HFA)(4)Net(4) and Eu(HFA)(4)Net(4), are quite stable and show no evidence of dissociation. We further characterize the dissociation of several chromophore systems and discuss the influence such dissociation has on overall optical performance. The results enable determination of optimal doping concentrations as well as preferred rare-earth chromophore preparation and doped polymer fabrication procedures.
    No preview · Article · Nov 1998 · Applied Optics
  • O. Zamani-Khamiri · A. Panakal · Yongming Cai · Anthony F. Garito
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    ABSTRACT: The second order nonlinear optical responses of two dipolar thiopheno-quinoid chromophores are calculated using extensive single and double-excitation configuration interaction (SDCI). The beta (-2 omega; omega, omega) values are found to be comparable in magnitude to those for the pheno-quinoid systems. The sign of the nonlinear response is, however, found to be positive in these systems, in contrast to the second-order nonlinear optical response of pheno-quinoid structures which are known to be negative.
    No preview · Article · Oct 1998 · Proceedings of SPIE - The International Society for Optical Engineering
  • AF Garito · J Wang · R Gao
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    ABSTRACT: REVIEW The most important feature of an optical fiber waveguide is its bandwidth, which defines its information-carrying capacity. A major limitation on the bandwidth of multimode glass and plastic optical fibers is modal dispersion, in which different optical modes propagate at different velocities and the dispersion grows linearly with length. However, in plastic optical fibers, experimental and theoretical results indicate that the modes are not independent but are highly coupled, which leads to a characteristic square-root length dependence and an unanticipated large enhancement of the bandwidth to gigahertz levels. The ever increasing demands for low-cost, high-bandwidth communications media for voice, video, and data transmission in short- and medium-distance applications are generating a new assessment of multimode optical fibers to serve as high-speed fiber links.
    No preview · Article · Sep 1998 · Science

Publication Stats

8k Citations
573.07 Total Impact Points

Institutions

  • 1971-2007
    • University of Pennsylvania
      • • Laboratory for Research on the Structure of Matter
      • • Department of Physics and Astronomy
      Philadelphia, PA, United States
  • 1975-2003
    • Philadelphia University
      Filadelfia, Pennsylvania, United States
  • 2000
    • Photon-x
      Kissimmee, Florida, United States
  • 1975-1998
    • William Penn University
      Filadelfia, Pennsylvania, United States
  • 1991
    • RIKEN
      Вако, Saitama, Japan