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Spectroelectrochemical sensing based on multimode selectivity simultaneously achievable in a single device. 9. Incorporation of planar waveguide technology

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ANALYTICAL CHEMISTRY 2000年第22期72卷 5549-5555页

作者： Ross, SE Seliskar, CJ Heineman, WR Univ Cincinnati Dept Chem Cincinnati OH 45221 USA

Incorporation of planar waveguide technology into a spectroelectrochemical sensor is described. In this sensor design, a potassium ion-exchanged BK7 glass waveguide was over-coated with a thin film of indium tin oxide (ITO) that served as an optically transparent electrode. A chemically selective film was spin-coated on top of the ITO film. The sensor supported five optical modes at 442 nm and three at 633 nm. Investigations on the impact of the ITO film on the optical properties of the waveguide and on the spectroelectrochemical performance of the sensor are reported. Sensing was based on the change in attenuation of light propagated through the waveguide resulting from an optically absorbing analyte, By applying either a triangular or square wave excitation potential waveform, electromodulation of the optical signal has been demonstrated with Fe(CN)(6)(3-/4-) as a model electroactive couple that partitions into a PDMDAAC-SiO2 film {where PDMDAAC = poly(dimethyldiallylammonium chloride)} and absorbs at 442 nm.

关键词： optical wave-guides Indium tin oxide K+-ion exchange Thin-films Spectroscopic ellipsometry Evaporated indium Sensor Glass Electrodes Electrochemistry

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Conducting polymer growth in porous sol-gel thin films: Formation of nanoelectrode arrays and mediated electron transfer to sequestered macromolecules

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CHEMISTRY OF MATERIALS 2005年第14期17卷 3652-3660页

作者： Doherty, WJ Armstrong, NR Saavedra, SS Univ Arizona Dept Chem Tucson AZ 85721 USA

We show the templated electrochemical growth of poly(3,4-ethylenedioxythiophene) (PEDOT) into porous sol-gel (PSG) films [50:50 tetraethyl orthosilicate/methyltriethoxysilane (TEOS/MTES)] on indium-tin oxide (ITO) substrates and PEDOT-mediated electron transfer to ferrocene-modified dendrimers encapsulated within these sol-gel matrices. We first describe conditions needed to optimize PEDOT electropolymerization within the porous sol-gel (PSG) films such that barely emergent PEDOT features, ca. 100 nm in diameter, protrude from a PSG thin film surface, functioning as an array of ultramicroelectrodes in diffusion controlled oxidation/reduction reactions of solution probe molecules. We next describe the incorporation of fourth-generation PAMAM dendrimers into these PSG films after (a) conjugation with ferrocenecarboxylic acid (Fc-COOH) to form Fc-PAMAM, (b) conjugation with both Fc-COOH and 3-thiopheneacetic acid (3TAA), or (e) conjugation with both Fc-COOH and 3,4-ethylenedioxythiophenemethanol (2,3-dihydrothieno[3,4-b]-1,4-dioxyn-2-yl or EDTM). Oxidation/reduction of the encapsulated Fc-PAMAM units could be voltammetrically detected after PEDOT growth into the sol-gel film, but with different efficiency, depending upon the composition of the encapsulated dendrimer. Background corrected cyclic voltammograms showed that ca. 0.9% of the ferrocene groups became electrochemically active when Fc-PAMAM alone was incorporated into the PSG film. Up to ca. 20% of these Fc-PAMAM units became electrochemically active, with high rates of electron transfer, when EDTM was conjugated to the Fc-PAMAM dendrimer and when the EDOT monomer was codoped into the sol-gel film. These results argue for the direct, facile electrochemical communication of encapsulated Fc,EDTM-PAMAM units to the ITO substrate via the electrochemically grown PEDOT "wires," especially when the conducting polymer and the Fc units are held in close proximity on the dendrimer. This is a new approach to control of the

关键词： optical wave-guides ELECTROCHEMICAL GROWTH SINGLE DEVICE SILICA POLY(3 4-ETHYLENEDIOXYTHIOPHENE) PROTEINS MATRICES SENSORS 3 4-ETHYLENEDIOXYTHIOPHENE POLYTHIOPHENE

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Three-dimensional finite-element beam propagation method: assessments and developments

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JOURNAL OF THE optical SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2000年第6期17卷 1124-1131页

作者： Vincetti, L Cucinotta, A Selleri, S Zoboli, M Univ Parma Dipartimento Ingn Informaz I-43100 Parma Italy Univ Modena Dipartimento Sci Ingn I-41100 Modena Italy

In recent years the finite-element method (FEM) has been widely applied to three-dimensional beam propagation analysis, and several FEM propagators have been presented. Up to now, as far as me know, an exhaustive, deep, and comparative analysis of these formulations and of the related algorithms has never been presented. We critically analyze and numerically compare, to our knowledge for the first time, different vectorial, semivectorial, and scaler formulations in order to check their performances, point out weaknesses, and suggest future developments. The results obtained highlight once more the inadequacy of scaler approaches in dealing with actual photonics devices and suggest vector formulations worthy of further development and future research. (C) 2000 optical Society of America [S0740-3232(00)01206-0].

关键词： Passive polarization converter optical wave-guides Integrated-optics Scheme

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NEW wave-GUIDE MODES IN ANISOTROPIC STRUCTURES

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FIBER AND INTEGRATED OPTICS 1994年第3期13卷 271-280页

作者： TORNER, L SANTOS, C TORRES, JP MIHALACHE, D INST ATOM PHYS DEPT THEORET PHYSBUCHARESTROMANIA

The existence of new hybrid waveguide modes of properly tailored integrated optical waveguides consisting of ultrathin films clad by positive birefringent media is pointed out.

关键词： optical wave-guides

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POLARIZATION-DEPENDENT COUPLING IN TWIN-CORE FIBERS WITH ARBITRARY ELLIPTIC CORES

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IEE PROCEEDINGS-OPTOELECTRONICS 1994年第1期141卷 43-48页

作者： HEWLETT, SJ LOVE, JD TJUGIARTO, T UNIV NEW S WALES SCH ELECT ENGNKENSINGTONNSW 2033AUSTRALIA

Polarisation-dependent coupling in a twin-elliptical-core optical fibre, whose cores possess both an arbitrary core eccentricity and orientation, is investigated. Exact numerical results are presented that determine the degree of form birefringence and permit the accuracy of standard approximation techniques to be evaluated. A comparison of the theoretical x-and y-polarisation coupling coefficients with experimental data suggests that stress-induced birefringence is dominant in practice.

关键词： FIBERS optical optical FIBERS optical SENSORS optical wave-guides

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Monte Carlo simulation studies of sidewall roughening during reactive ion etching

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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 2007年第2期88卷 401-407页

作者： Pani, S. K. Tjiptoharsono, F. Wong, C. C. Premachandran, C. S. Ramama, P. V. Iyer, M. K. Nanyang Technol Univ Sch Mat Engn Singapore 639798 Singapore Inst Microelect Singapore 117685 Singapore

The evolution of sidewall roughness (SWR) during reactive ion etching (RIE) was simulated using a Monte Carlo method. It was discovered that the sidewall roughness established during an earlier etch period represents a historical archive of the moment during which the etch front passes by and is not affected by further etching. We also found that the behavior of SWR follows two distinct trends. At the initial stages, SWR increases with etch time, or its equivalent, the etch depth, but, beyond a certain etch depth, SWR of etched surfaces stabilizes and does not change with further etching. This is related to the change of the number of shadowing and reemitted particles as the etch depth increases. When the shadowing sticking coefficient decreases significantly, SWR increases beyond a certain critical depth due to reemission. Additionally, the noise also increases as the sticking coefficient decreases because of an increased number of reemitted particles. The simulated results support very well the assertions and mechanisms of the experimental findings and an etch model based on shadowing and first-order reemission effects at low RIE pressure.

关键词： optical wave-guides POLYIMIDE FILMS ROUGHNESS DIMENSIONS EVOLUTION

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Matrix analysis of 2D microring resonator arrays

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JOURNAL OF MODERN OPTICS 2008年第1期55卷 143-154页

作者： Ma, Chun-Sheng Yan, Xin Wang, Xian-Yin Jilin Univ Coll Elect Sci & Engn State Key Lab Integrated Optoelect Changchun 130012 Peoples R China Changchun Univ Sci & Technol Changchun 130012 Peoples R China

In terms of the coupled mode theory and the transfer matrix technique, novel formulas of the transfer functions are presented for a 2D microring resonator (MRR) array, which consists of two straight buslines, N parallel-cascaded columns, each of which contains M series-coupled rings. By using these formulas, the parameters are optimized, and the transmission characteristics including the transmission spectrum and the insertion loss are analysed for such a 2D SiN/SiO2 MRR array. By properly selecting the distance between adjacent columns, the amplitude coupling ratio between the busline and the ring and that between adjacent rings, as well as the number of the rows and that of the columns, the box-like spectral response is successfully obtained, the passband is precipitous, and the non-resonant light and crosstalk are weak.

关键词： optical wave-guides RING-RESONATOR FILTERS SYSTEMS SIN

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REFRACTIVE-INDEX-PROFILE DETERMINATIONS BY USING LLYOD MIRAGE

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APPLIED OPTICS 1994年第10期33卷 1806-1811页

作者： ALLMAN, BE KLEIN, AG NUGENT, KA OPAT, GI []The authors are with the School of Physics The University of Melbourne Parkville Victoria 3052 Australia.

A method is presented for the experimental determination of refractive-index profiles for planar media of monotonically decreasing refractive index, such as those used for optical waveguides. The technique is based on a generalization of the classical experiment of Lloyd's mirror, involving the interference pattern formed by a point source and its mirage, i.e., its reflection in such a graded planar medium.

关键词： GRADED INDEX OPTICS INTEGRATED OPTICS optical wave-guides MIRAGE

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Light propagation within colloidal crystal wire fabricated by a dewetting process

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NANO LETTERS 2008年第3期8卷 853-858页

作者： Mitsui, Tadashi Wakayama, Yutaka Onodera, Tsunenobu Takaya, Yosuke Oikawa, Hidetoshi Natl Inst Mat Sci Quantum Dot Res Ctr Tsukuba Ibaraki 3050044 Japan Natl Inst Mat Sci Adv Elect Mat Ctr Tsukuba Ibaraki 3050044 Japan Tohoku Univ Inst Multidisciplinary Res Adv Mat Sendai Miyagi 9808577 Japan

We present a colloidal crystal wire composed of thousands of connected microspheres that is fabricated by a simple dewetting process utilizing a drain phenomenon, and we directly observe the light propagation within the wire by near-field scanning optical microscopy. The optical properties of propagation light suggest that the propagation mechanism was attributed mainly to nanojet-induced mode coupling for the straight propagation component and partly to whispering-gallery mode coupling within the colloidal crystal wire.

关键词： optical wave-guides PHOTONIC CRYSTALS MICROSPHERES MICROSCOPE BENDS TRANSMISSION INTEGRATION SPECTRA CHAINS CHIP

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Controllable formation of nanoscale patterns on TiO₂ by conductive-AFM nanolithography

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LANGMUIR 2008年第16期24卷 8944-8949页

作者： Garipcan, B. Winters, J. Atchison, J. S. Cathell, M. D. Schiffman, J. D. Leaffer, O. D. Nonnenmann, S. S. Schauer, C. L. Piskin, E. Nabet, B. Spanier, J. E. Drexel Univ Dept Mat Sci & Engn Philadelphia PA 19104 USA Hacettepe Univ Dept Chem Engn Bioengn Div TR-06800 Ankara Turkey

We report on the nanopatteming of double-bond-terminated silane (5-hexenyltrichlorosilane, HTCS) molecules on titania (TiO2) using conductive atomic force microscopy (AFM). The influences of tip electrostatic potential and scanning velocity, relative humidity and of the repeated application of voltage on the topographic height, width, and hydrophilic and hydrophobic contrast of the resultant patterns were investigated. Tip voltage and tip velocity (v) were applied between -10 V <= V-tip <= +10 V and 100 nm/s <= v <= 2 mu m/s during the lithography step(s), respectively. Average height and Lateral Force Mode (LFM) images of patterns were obtained with different values of(-10 V <= V-tip <= -7 V) and v (100 nm/s <= v <= 2 mu m/s). The average height of the patterns is seen to decrease for increasing v and decreasing V-tip in both a single or repeated lithography step. No patterns were observed following a single or repeated lithography step for -5 V <= V-tip <= +10 V. This conductive lithography technique results in nanoscale physiochemical manipulations of the HTCS molecules that are manifested as controllable step heights ranging from similar to 1-15 nm possessing different chemistries on the patterned and unpatterned areas. The use of conductive-AFM nanolithography for altering and manipulating double-bond-terminated molecules on TiO2 surfaces suggests a range of applications, including selective immobilization and assembly of functionalized inorganic nanoparticles and biomolecules.

关键词： ATOMIC-FORCE MICROSCOPY DIP-PEN NANOLITHOGRAPHY SELF-ASSEMBLED MONOLAYERS optical wave-guides CHEMICAL-MODIFICATION COMPOSITE-MATERIALS SILICON SURFACES NANOSTRUCTURES FABRICATION FILMS

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