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Holographic gratings in photorefractive materials: A review

LASER PHYSICS 2007年第3期17卷 231-243页

作者： Passaro, V. M. N. Magno, F. Politecn Bari Photon Res Grp Dipartimento Elettr & Elettr I-70125 Bari Italy

In this paper, the fundamental characteristics of the photorefractive effect, both in bulk crystals and waveguides, as well as some of the most important photorefractive materials, their properties, and applications, are reviewed. In the last section, we report some experimental considerations on diffracted power from holograms written in pure LiNbO3 and Fe:LiNbO3 crystals and waveguides.

关键词： LITHIUM-NIOBATE CRYSTALS BARIUM-CALCIUM-TITANATE CHARGE-TRANSPORTPROCESSES wave-guides TEMPERATURE-DEPENDENCE ELECTROOPTIC CRYSTALS POLYMER COMPOSITES LASER-PULSES STORAGE waveLENGTH

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Boundaryless finite-difference method for three-dimensional beam propagation

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2006年第4期23卷 866-871页

作者： Guizar-Sicairos, M Gutiérrez-Vega, JC Tecnol Monterrey Photon & Math Opt Grp Monterrey 64849 Mexico

A two-dimensional optical field paraxial propagation scheme, in Cartesian and cylindrical coordinate systems, is proposed. This is achieved by extending the method originally proposed by Ladouceur [Opt. Lett. 21, 4 (1996)] for boundaryless beam propagation to two-dimensional optical wave fields. With this formulation the arbitrary choice of physical window size is avoided by mapping the infinite transverse dimensions into a finite-size domain with an appropriate change of variables, thus avoiding the energy loss through the artificial physical boundary that is usually required for the absorbing or the transparent boundary approach. (c) 2006 Optical Society of America.

关键词： MAPPED INFINITE DOMAINS TRANSPARENT BOUNDARY wave-guides

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Protein adsorption kinetics under an applied electric field: An optical waveguide lightmode spectroscopy study

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LANGMUIR 2003年第12期19卷 5089-5097页

作者： Brusatori, MA Tie, Y Van Tassel, PR Wayne State Univ Dept Chem Engn & Mat Sci Detroit MI 48202 USA

The controlled surface placement of protein molecules represents a crucial step toward many new biotechnological devices and processes. A promising means of directing the structure and formation rate of an adsorbed protein layer is through an applied electric potential difference. We present here a method for continuously measuring the protein adsorption under a direct current voltage using optical waveguide lightmode spectroscopy. An indium tin oxide-coated waveguiding sensor chip serves as the anode and adsorbing substrate, and a platinum counter electrode serves as the cathode in a parallel plate arrangement. For (negatively charged) human serum albumin in either pure water or N-[2-hydroxyethyl]piperazine-N'-ethanesulfonic acid (HEPES) buffer, we find the transport-limited and initial surface-limited rates of adsorption to significantly increase with the applied potential. For (positively charged) horse heart cytochrome c, we observe no influence of the voltage on the transport-limited adsorption rate in either solvent and a decrease with the voltage in the initial surface-limited rate in a HEPES (but not a pure water) solvent. Interestingly, we find the rate of adsorption at moderate to high surface density to greatly increase with the voltage for both proteins;this effect is more pronounced in water than in HEPES. We attribute this enhanced adsorption to contact between electrode and protein patches of complementary charge, leading to more oriented and efficiently packed adsorbed molecules and, in the case of high voltage, to multilayer formation.

关键词： Bovine serum-albumin Internal-reflection fluorescence Random sequentialadsorption Assembled polyelectrolyte films wave-guides Brownian dynamics Grating couplers Surface-charge Crystallization conditions Lysozyme adsorption

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SLOTTED PARALLEL-PLATE wave-GUIDE COUPLED TO A CONDUCTING CYLINDER

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IEE PROCEEDINGS-H MICROwaveS ANTENNAS AND PROPAGATION 1992年第2期139卷 193-201页

作者： MANNIKKO, PD COURTNEY, CC BUTLER, CM College of Engineering Department of Electrical and Computer Engineering Clemson University Clemson USA

The problem of electromagnetic scattering from a perfectly electrically conducting cylinder in the presence of a slot in a parallel-plate waveguide is considered. A two-dimensional slot in one of the walls of the parallel-plate guide opens into a half-space in which the two-dimensional conducting cylinder resides. The excitation for this structure is an incident TEM wave from within the waveguide, and/or a magnetic line source which produces an incident TE(y) wave in the exterior half-space. Coupled integral equations for the aperture electric field and the cylinder current are derived from first principles and are solved numerically for cylinders of various cross-section, size, and location relative to that of the slot aperture. From knowledge of the aperture electric field and cylinder current, all other quantities of interest may be determined. For TEM excitation from within the guide, the reflection coefficient and radiation pattern data are presented along with the aperture electric field and cylinder current. For external excitation, data are presented that illustrate how the cylinder serves as a shield for the aperture. From this data one can assess the effectiveness of a conducting shield placed over, but not in contact with, the guide aperture.

关键词： wave-guides ELECTROMAGNETIC THEORY

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Solitons in one-dimensional photonic crystals

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2008年第11期25卷 1854-1863页

作者： Mayteevarunyoo, Thawatchai Malomed, Boris A. Tel Aviv Univ Sch Elect Engn Fac Engn Dept Phys Elect IL-69978 Tel Aviv Israel Mahanakorn Univ Technol Dept Telecommun Engn Bangkok 10530 Thailand

We report on results of a systematic analysis of spatial solitons in the model of one-dimensional photonic crystals, built as a periodic lattice of waveguiding channels, of width D, separated by empty channels of width L -D. The system is characterized by its structural "duty cycle," DC equivalent to D/L. In the case of the self-defocusing (SDF) intrinsic nonlinearity in the channels, one can predict new effects caused by competition between the linear trapping potential and the effective nonlinear repulsive one. Several species of solitons are found in the first two finite bandgaps of the SDF model, as well as a family of fundamental solitons in the semi-infinite gap of the system with the self-focusing nonlinearity. At moderate values of DC (such as 0.50), both fundamental and higher-order solitons populating the second bandgap of the SDF model suffer destabilization with an increase of the total power. Passing the destabilization point, the solitons assume a flat-top shape, while the shape of unstable solitons gets inverted with local maxima appearing in empty layers. In the model with narrow channels (around DC=0.25), fundamental and higher-order solitons exist only in the first finite bandgap, where they are stable, despite the fact that they also feature the inverted shape. (C) 2008 Optical Society of America

关键词： SPATIAL SOLITONS wave-guides OPTICAL LATTICES LOCALIZED MODES GAP SOLITONS FIBERS GENERATION Fiber Solitons Band gap DESTABILIZATION optical lattices higher-order waveguide Device Component narrow passage Photonic crystals

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Observation of the complex propagation of a femtosecond laser pulse in a dispersive transparent bulk material

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2003年第3期20卷 597-602页

作者： Kumagai, H Cho, SH Ishikawa, K Midorikawa, K Fujimoto, M Aoshima, S Tsuchiya, Y RIKEN Laser Technol Lab Wako Saitama 3510198 Japan Hamamatsu Photon KK Cent Res Lab Shizuoka 4348601 Japan

Pulse shapes in a dispersive transparent material modulated by group-velocity dispersion, self-phase modulation, and self-focusing induced by a femtosecond laser light were observed directly with femtosecond time-resolved optical polarigraphy probing the induced instantaneous birefringence. The first observation of the state of femtosecond laser pulses about the interaction region inside the transparent bulk material indicated that the pulse propagation was accomplished with a multiple conelike structure that was hypothesized from a numerical simulation with an extended nonlinear Schrodinger equation. (C) 2003 Optical Society of America.

关键词： Varying envelope approximation Resolved optical polarigraphy wave-guides Plasma Breakdown Light Generation Dynamics Air

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Tuned graft copolymers as controlled coatings for DNA microarrays

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ANALYTICAL CHEMISTRY 2005年第18期77卷 5831-5838页

作者： De Paul, SM Falconnet, D Pasche, S Textor, M Abel, AP Kauffmann, E Liedtke, R Ehrat, M ETH Swiss Fed Inst Technol Dept Mat Surface Sci & Technol Lab CH-8093 Zurich Switzerland Zeptosens AG CH-4108 Witterswil Switzerland

DNA microarrays have become a powerful tool for expression profiling and other genomics applications. A critical factor for their sensitivity is the interfacial coating between the chip substrate and the bound DNA. Such a coating has to embrace the divergent requirements of tightly binding the capture probe DNA during the spotting process and of minimizing the nonspecific binding,of target DNA during the hybridization assay. To fulfill these conditions, most coatings require a passivation step. Here we demonstrate how the chain density of a graft copolymer with a polycationic backbone, poly(L-lysine)-graft-poly(ethylene glycol), can be tuned such that the binding capacity during capture probe deposition is maximized while the nonspecific binding during hybridization assays is kept to a minimum, thus alleviating the requirement for a separate passivation procedure. Evidence for the superior performance of such coatings in terms of signal-to-noise ratio and spot quality is presented using an evanescent field-based fluorescent sensing technique (the ZeptoREADER). The surface architecture is further characterized using optical waveguide lightmode spectroscopy and time-of-flight secondary ion mass spectrometry. Finally, in a model assay, we demonstrate that expression changes can be detected from 1 mu g of total mRNA sample material with a limit of detectable differential expression of +/- 1.5.

关键词： METAL-OXIDE SURFACES POLY(L-LYSINE)-G-POLY(ETHYLENE GLYCOL) LAYERS PROTEIN ADSORPTION GENE-EXPRESSION wave-guides RESISTANCE ARCHITECTURE MONOLAYERS INTERFACE CDNA Monolayers Graft copolymers Interfaces waveguide Device Component Chromosomal Probes ARCHITECTURE Protein adsorption tuning Building construction Complementary DNA Passivation metal oxides Interface

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Fabrication and characterization of two-photon polymerized features in colloidal crystals

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ADVANCED FUNCTIONAL MATERIALS 2005年第12期15卷 1995-2004页

作者： Pruzinsky, SA Braun, PV Univ Illinois Dept Mat Sci & Engn Beckman Inst Adv Sci & Technol Urbana IL 61801 USA Univ Illinois Frederick Seitz Mat Res Lab Urbana IL 61801 USA

The fabrication and characterization of two photon polymerized features written within and outside of colloidal crystals is presented. Two-photon polymerization (TRP) response diagrams are introduced and developed to map the polymerization and damage thresholds for features written via modulated beam rastering. The use of tris[4-(7-benzothiazol-2-yl-9,9-diethylfluoren-2-yl)phenyl]amine (AF 350) as an initiator for TPP is demonstrated for the first time and TPP reponse diagrams illustrate the polymerization window. These diagrams also demonstrate that the polymerization behavior within and outside of colloidal crystals is similar and electron microscopy reveals nearly identical resolution. Fluorescence confocal microscopy further enables visualization of non-self-supporting, three-dimensional TPP features within self-assembled photonic crystals. Finally, microspot spectroscopy is collected from a two photon feature written within a colloidal crystal and this is compared with simulation.

关键词： PHOTONIC CRYSTALS SILICA SPHERES DIFFRACTION RESPONSE NUMERICAL-APERTURE wave-guides PHOTOPOLYMERIZATION ABSORPTION MICROFABRICATION EXCITATION MICROSCOPY

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High-order harmonic and attosecond pulse generation for a few-cycle laser pulse in modulated hollow fibres

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JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS 2007年第14期40卷 2917-2925页

作者： Zhang, Xiangyun Sun, Zhenrong Wang, Yufeng Chen, Guoliang Wang, Zugeng Li, Ruxin Zeng, Zhinan Xu, Zhizhan E China Normal Univ Dept Phys Minist Educ Key Lab Opt & mAgnet Resonance Spect Shanghai 200062 Peoples R China E China Normal Univ Dept Math Shanghai 200062 Peoples R China

High harmonic generation from Ar and He atoms by a few-cycle laser pulse in periodic and chirped hollow fibres is investigated theoretically by a self-consistent model. Based on enhanced high harmonics in a periodic hollow fibre, a chirped hollow fibre is proposed to improve quasi-phase matching for the generated harmonics near the cutoff. The results show that the extended and enhanced harmonics near the cutoff are well phase-matched, and a single x-ray pulse with a duration of 279 as in Ar gas and 255 as in He gas can be achieved by frequency synthesizing of high harmonics in the well-selected cutoff bandwidth. The results show that this technique is a potential candidate to generate an intense isolated attosecond pulse in the 'water window' spectrum.

关键词： PHASE-MATCHED GENERATION SOFT X-RAYS wave-guides PROPAGATION DYNAMICS

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Second-harmonic generation in reflection and diffraction by a GaAs photonic-crystal waveguide

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2002年第9期19卷 2122-2128页

作者： Malvezzi, AM Cattaneo, F Vecchi, G Falasconi, M Guizzetti, G Andreani, LC Romanato, F Businaro, L Di Fabrizio, E Passaseo, A De Vittorio, M Univ Pavia Ist Nazl Fis Mat I-27100 Pavia Italy Univ Pavia Dipartimento Elettron I-27100 Pavia Italy Univ Pavia Dipartimento Fis A Volta I-27100 Pavia Italy Elettra Synchrotron Light Source TASC Ist Nazl Fis Mat Nanolithog Beamline Natl Nanotechnol Lab I-34012 Trieste Italy Univ Lecce Ist Nazl Fis Mat Natl Nanotechnol Lab I-73100 Lecce Italy Univ Lecce Dipartimento Ingn Innovaz I-73100 Lecce Italy

Nonlinear reflection and diffraction measurements have been performed on a GaAs/AlGaAs photonic-crystal waveguide patterned with a square lattice: The basis in the two-dimensional unit cell consists of rings of air in the dielectric matrix. The measured angles of diffracted second-harmonic beams agree with those predicted for nonlinear diffraction conditions. Results for second-harmonic intensities as a function of incidence angle, polarization, and pump wavelength show that the reflected second-harmonic signal is dominated by the crystalline symmetry of GaAs, whereas nonlinear diffraction is determined by the photonic-crystal structure. (C) 2002 Optical Society of America.

关键词： Enhanced 2nd-harmonic generation Near-infrared wavelengths Surface-diffusion Selective enhancement wave-guides Optics Co Reflection Optics gallium arsenides second harmonics waveguide Device Component Second-harmonic generation diffraction surface diffusion

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