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Multiple phase production on doping Er³⁺ into α-Al₂O₃

CHEMICAL PHYSICS LETTERS 2004年第1-3期399卷 15-19页

作者： Tanner, PA Wong, KL Liang, Y City Univ Hong Kong Dept Biol & Chem Kowloon Hong Kong Peoples R China

Samples of alpha-Al2O3 were prepared by the preformed sol or nitrate-citrate methods and were doped with Er3+ at concentrations from 25 to 0.1 at.%. The luminescence spectra showed the formation of erbium garnet and/or perovskite compounds and no luminescence from Er3+ substituted at Al3+ sites was detected. This contrasts with previous reports, especially the low-temperature luminescence of alpha-Al2O3:Er3+ (1 at.%) which in fact corresponds to ErAlO3, (C) 2004 Elsevier B.V. All rights reserved.

关键词： SOL-GEL METHOD PULSED-LASER DEPOSITION AL2O3 THIN-FILMS OPTICAL-SPECTRA ENERGY-LEVELS CRYSTAL-FIELD wave-guides METAL-IONS LUMINESCENCE PHOTOLUMINESCENCE

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Complete modulational-instability gain spectrum of nonlinear quasi-phase-matching gratings

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2004年第3期21卷 617-621页

作者： Corney, JF Bang, O Univ Queensland Dept Phys St Lucia Qld 4072 Australia Tech Univ Denmark Res Ctr COM DK-2800 Lyngby Denmark

We consider plane waves propagating in quadratic nonlinear slab waveguides with nonlinear quasi-phase-matching gratings. We predict analytically and verify numerically the complete gain spectrum for transverse modulat... 详细信息

关键词： wave-guides SPATIAL SOLITONS QUADRATIC MEDIA GENERATION

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Mode dispersion and photonic storage in planar defects within Bragg stacks of photonic crystal slabs

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2004年第3期21卷 522-530页

作者： Dridi, KH NKT Res & Innovat AS DK-3460 Birkerod Denmark

It is shown that electromagnetic energy can be localized to defect regions bounded by parallel planar walls perpendicular to the stack surface in Bragg stacks of two-dimensional photonic crystals. These regions produce larger bandgaps than single-photonie-crystal slabs. Group velocity and dispersion relations can easily be tailored by choice of the proper geometry and materials. Results indicate that such photonic crystals might facilitate photonic trapping and storage together with advanced photonic manipulations. (C) 2004 Optical Society of America

关键词： wave-guides waveLENGTHS BANDGAP FIBERS LIGHT

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Scalable electrothermal MEMS actuator for optical fibre alignment

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JOURNAL OF MICROMECHANICS AND MICROENGINEERING 2004年第12期14卷 1633-1639页

作者： Syms, RRA Zou, H Yao, J Uttamchandani, D Stagg, J Univ London Imperial Coll Sci & Technol Opt & Semicond Devices Grp Dept Elect & Elect Engn London SW7 2BT England Univ Strathclyde Dept Elect & Elect Engn Glasgow G1 1XW Lanark Scotland

A new geometry of high-force electrothermal actuator is demonstrated using microelectromechanical systems technology. The actuator consists of two sets of inclined, parallel, suspended beams, which are tethered at one end and linked together at the other. The first set is divided into two halves, which are connected in series and heated electrically. The second set acts as a tether for the first, so that differential thermal expansion gives rise to a lateral deflection. The design can be scaled easily to increase the actuation force, which is sufficient to deflect a cantilevered optical fibre. A bi-directional fibre alignment device is formed from two opposed actuators, which are designed to grip the fibre, and a set of fixed mounting features. Prototype devices are demonstrated by deep reactive ion etching of bonded silicon-on-insulator, and in-plane alignment of single-mode fibre is demonstrated.

关键词： wave-guides SILICON SWITCHES

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Counterpropagating quasi-phase matching: a generalized analysis

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2004年第8期21卷 1509-1521页

作者： Landry, GD Maldonado, TA Texas A&M Univ College Stn TX 77843 USA

The system of four differential equations governing counterpropagating quasi-phase matching are recast in a Hamiltonian form that leads to immediate insight into the nonlinear mixing process by inspection for all possible boundary conditions. A reduced Hamiltonian is found using conservation relations that are dependent on only two normalized field efficiencies and two aggregate phases. Hamiltonian contours are plotted in a series of phase-space cross sections to provide insight into the generalized behavior. The nonlinear eigenmodes are found, and their stability is examined. Finally, two specific counterpropagating quasi-phasematching configurations, i.e., mirrored and mirrorless, are analyzed using this general Hamiltonian with the appropriate boundary conditions. (C) 2004 Optical Society of America.

关键词： CASCADED 2ND-ORDER PROCESSES POLED LITHIUM-NIOBATE BACKWARD 2ND-HARMONICGENERATION wave-guides FREQUENCY-GENERATION NONLINEAR MEDIUM BULK LINBO3 CONFIGURATION CHI((2)) LIGHT

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Optical properties of perfluorocyclobutyl polymers. II. Theoretical and experimental attenuation

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2004年第5期21卷 958-967页

作者： Ballato, J Foulger, SH Smith, DW Clemson Univ Sch Mat Sci & Engn Ctr Opt Mat Sci & Engn Technol Clemson SC 29634 USA Clemson Univ Dept Chem Ctr Opt Mat Sci & Engn Technol Clemson SC 29634 USA

We present a continuation of a previous study [J. Opt. Soc. Am. B 20, 1838 (2003)] that focused on quantifying the spectral dependence of the refractive index and extinction coefficient of perfluorocyclobutyl (PFCB)-based polymers. The theoretical loss spectrum of PFCB-based polymers is computed and compared with measured values on thick films over the spectral range covering the visible and near-infrared telecommunications bands. The results suggest that PFCB-based polymers provide for intrinsic attenuations below 10 dB/km in the visible and from 1.3 to 1.6 mum. The results are used to predict directions for the use of PFCB in optical fibers, planar lightwave circuits, and optical amplifiers. (C) 2004 Optical Society of America

关键词： TRANSPARENT AMORPHOUS POLYMERS wave-guides FIBERS ABSORPTION ROUGHNESS

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Quasi-free-space optical coupling between diffraction grating couplers fabricated on independent substrates

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APPLIED OPTICS 2004年第29期43卷 5468-5475页

作者： Mulé, AV Villalaz, R Gaylord, TK Meindl, JD Georgia Inst Technol Microelect Res Ctr Atlanta GA 30332 USA

Optical coupling between preferential-order volume diffraction grating couplers fabricated on independent substrates is demonstrated. The coupling efficiency between gratings is quantified as a function of both grating and waveguide fabrication technology and relative angular position of the two substrates. A maximum grating-to-grating coupling efficiency of 31% is reported for coupling between two nonoptimized, nonfocusing, unpatterned volume grating couplers. (C) 2004 Optical Society of America.

关键词： wave-guides PHOTOPOLYMERS Diffraction gratings couplers COUPLING EFFICIENCY Optical coupling photopolymers waveguide Device Component Substrates INTERCHAIN COUPLING

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Controllable Raman-like nonlinearities from nonstationary, cascaded quadratic processes

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2004年第2期21卷 376-383页

作者： Ilday, FÖ Beckwitt, K Chen, YF Lim, H Wise, FW Cornell Univ Dept Appl & Engn Phys Ithaca NY 14853 USA

We show that useful noninstantaneous, nonlinear phase shifts can be obtained from cascaded quadratic processes in the presence of group-velocity mismatch. The two-field nature of the process permits responses that can be effectively advanced or retarded in time with respect to one of the fields. There is an analogy to a generalized Raman-scattering effect, permitting both red and blueshifts of short pulses. We expect this capability to have many applications in short-pulse generation and propagation, such as the compensation of Raman-induced effects and high-quality pulse compression, which we discuss. (C) 2004 Optical Society of America.

关键词： SELF-FREQUENCY SHIFT PHASE MODULATION wave-guides MEDIA GENERATION SOLITONS SYSTEMS PULSES FIBER COMPRESSION

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Ultrafast optical tuning of a superprism effect in nonlinear photonic crystals

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2004年第8期21卷 1500-1508页

作者： Panoiu, NC Bahl, M Osgood, RM Columbia Univ Dept Appl Phys & Appl Math New York NY 10027 USA

A comprehensive analysis of an optically tunable superprism effect in a two-dimensional nonlinear photonic crystal is presented. We demonstrate that, under certain circumstances, if one modifies the band structure of the crystal through the Kerr effect induced by a pump beam, the refraction angle of the transmitted signal beam can be tuned over tens of degrees. Two complementary geometries are considered, namely, air holes in a dielectric background and dielectric rods surrounded by air, and in both cases the TE and TM polarizations are studied. We also show that, because of the slow light effect, in both cases the optical power required to tune the refracted angle is dramatically reduced if the frequency of the pump beam is close to a photonic bandgap edge. (C) 2004 Optical Society of America.

关键词： INHIBITED SPONTANEOUS EMISSION BAND-GAP wave-guides LIGHTwave CIRCUITS HIGH TRANSMISSION FARADAY-ROTATION BOUND-STATES DEFECTS REFLECTIVITY ENHANCEMENT

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Nanowire photonic circuit elements

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NANO LETTERS 2004年第10期4卷 1981-1985页

作者： Barrelet, CJ Greytak, AB Lieber, CM Harvard Univ Dept Chem & Chem Biol Cambridge MA 02138 USA Harvard Univ Div Engn & Appl Sci Cambridge MA 02138 USA

We report an approach for guiding and manipulating light on sub-wavelength scales using active nanowire waveguides and devices. Quantitative studies of cadmium sulfide (CdS) nanowire structures show that light propagation takes place with only moderate losses through sharp and even acute angle bends. In addition, measurements demonstrate that efficient injection into and modulation of light through nanowire waveguides are achievable in active devices. The ability to inject, guide, and manipulate light on a sub-wavelength scale using nanowire components that can be assembled into integrated structures represents a promising pathway towards integrated nanoscale photonic systems.

关键词： wave-guides CRYSTAL TRANSMISSION LASERS BENDS

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