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Enhancement of light extraction from two-dimensional photonic crystal slab structures

IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS 2002年第2期8卷 231-237页

作者： Ryu, HY Hwang, JK Lee, YJ Lee, YH Korea Adv Inst Sci & Technol Dept Phys Taejon 305701 South Korea

Efficient light extraction from various two-dimensional photonic crystal slab structures is studied. By using the finite-difference time-domain method, effects of finite air-hole depth, and the cladding refractive index on the light extraction efficiency are investigated. The largest extraction efficiency is obtained in the photonic crystal slab with entirely drilled air hole patterns and large index contrast with the bottom cladding. Using InGaAsP quantum wells emitting at 1.5 mum large enhancement of photoluminescence is observed from the slab structures with air-hole patterns fully transferred through the active medium and the bottom cladding. The photoluminescence enhancement relative to the as-grown wafer is similar to8 in the oxide-supported slab and similar to13 in the free-standing slab. The large light extraction enhancement results from the coupling to leaky modes above the light line of a band structure. In addition, the extraction behaviors of a triangular lattice and a square lattice are compared, and it is shown that their distinctive extraction characteristics well reflect the features of each band structure.

关键词： extraction efficiency finite-difference time-domain method InGaAsP quantum well photoluminescence photonic crystal slab

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time-domain 2D modeling of slab-waveguide-based photonic-crystal devices in the presence of radiation losses

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MICROWAVE AND OPTICAL TECHNOLOGY LETTERS 2002年第5期34卷 387-393页

作者： Qiu, M Jaskorzynska, B Swillo, M Benisty, H Royal Inst Technol KTH Dept Microelect & Informat Technol Lab Photon & Microwave Engn S-16440 Kista Sweden Ecole Polytech Phys Mat Condensee Lab F-91128 Palaiseau France

Devices based on two-dimensional (2D) photonic crystals (PCs) arc typically realized as 3D structures consisting of an array of holes (or rods) vertically etched through a slab waveguide. The existence of holes in a slob waveguide may induce strong radiation losses to the slab claddings. Exact modeling of devices affected by such losses requires 3D calculations. In the present Letter, with the use of the effective-index method to account for the vertical confinement and the effective losses method by the nonvanishing conductivity, the 3D modeling is reduced into 2D. It is then shown that good agreement with experiments can be obtained for slab-waveguide-based photonic crystal devices. (C) 2002 Wiley Periodicals, Inc.

关键词： finite-difference time-domain method radiation losses photonic crystals photonic crystal waveguides

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Defect modes in a two-dimensional square-lattice photonic crystal

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OPTICS COMMUNICATIONS 2002年第4-6期209卷 229-235页

作者： Chung, KB Kim, SH Hongik Univ Sch Elect & Elect Engn Mapo Gu Seoul 121791 South Korea Korea Inst Sci & Technol Photon Res Ctr Seoul 130650 South Korea

This paper presents the transmission characteristics of defects with square and rectangular cross-section and different permittivity in a two-dimensional photonic crystal composed of circular cylinders on a square lattice. It has been observed particularly that a monomode and a quadruple mode, located closely, exist for a single square cross-section defect, and a symmetric and an antisymmetric modes, also located closely, exist for two missing-cylinder defects. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： photonic crystal defect modes finite-difference time-domain method

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Signal propagation effects on high-speed interconnection lines using time-domain numerical technique

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MICROWAVE AND OPTICAL TECHNOLOGY LETTERS 2002年第5期35卷 416-420页

作者： Li, EP Yuan, WL Wang, S Inst High Performance Comp Computat Electromagnet & Elect Div Singapore 117528 Singapore

With advancements in microelectronics, interest in electromagnetic interference and compatibility in high-speed circuits has greatly increased in the engineering community and application of computational electromagnetics to electromagnetic interference and compatibility (EMI/EMC) engineering has become an emerging technology. Termination, via, and crosstalk on interconnection lines raises EMI problems in high-speed circuits and requires attention during design phases for signal integrity. This paper analyzes signal propagation effects among different parts of high-speed interconnection lines using the finite-difference time-domain (FDTD) method. The mechanism and the effectiveness of control measures are examined, which can be applied to high-speed circuit designs. (C) 2002 Wiley Periodicals, Inc.

关键词： signal propagation effect high-speed interconnection lines finite-difference time-domain method

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Microstrip filter design using FDTD and neural networks

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MICROWAVE AND OPTICAL TECHNOLOGY LETTERS 2002年第3期34卷 219-224页

作者： Banciu, MG Ambikairajah, E Ramer, R Univ New S Wales Sch Elect Engn & Telecommun Sydney NSW 2052 Australia

A new design technique using the FDTD method and neural networks is applied to a microstrip filter. The total design time is reduced by two means. First, an iterative ARMA signal estimation technique is utilized to reduce the computation time for each FDTD run. Second, the number of FDTD simulations is decreased with the use of the device model provided by a neural network with the ARMA coefficients at the output. The trained network was then incorporated to an optimization procedure for a microstrip filter design. (C) 2002 Wiley Periodicals, Inc.

关键词： microstrip filters microwave design neural networks finite-difference time-domain method

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Transmitter-receiver-transmitter-configured ground-penetrating radars over randomly heterogeneous ground models -: art. no. 1094

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RADIO SCIENCE 2002年第6期37卷 6-1-6-9页

作者： Gürel, L Oguz, U Bilkent Univ Dept Elect & Elect Engn TR-06533 Bilkent Turkey

[1] Ground-penetrating radar (GPR) problems are simulated using the finite-difference time-domain (FDTD) method. The GPR model is configured with arbitrarily polarized three antennas, two of which are transmitting antennas fed 180degrees out of phase. The receiver is placed in the middle of two transmitters, where it receives no direct coupling from the transmitting antennas. The ground is modeled as a dielectric, lossy, and heterogeneous medium. The performances of the transmitter-receiver-transmitter-configured GPRs above the heterogeneous ground models are investigated. The computational domain is terminated by perfectly matched layer (PML) absorbing boundaries. The PML is adapted to match both air and ground regions of the computation space.

关键词： ground-penetrating radar finite-difference time-domain method perfectly matched layer

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Composite effects of reflections and ground bounce for signal line through a split power plane

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IEEE TRANSACTIONS ON ADVANCED PACKAGING 2002年第2期25卷 297-301页

作者： Wu, CT Shiue, GH Lin, SM Wu, RB Natl Taiwan Univ Grad Inst Commun Engn Dept Elect Engn Taipei 106 Taiwan

The signal propagating along a microstrip line over a slot on the power plane will suffer from composite effects of reflected noise by a discontinuity in signal return path and ground bounce between power and ground planes. A new equivalent circuit model is proposed and simulations are performed for multilayer structures to characterize these composite effects. An experimental setup is devised to demonstrate significant coupling between signal lines due to the slot-induced ground bounce. Favorable comparison between the simulation and measured results validates the proposed equivalent circuit model and analysis approach.

关键词： finite-difference time-domain method ground bounce printed circuit board signal integrity slot voltage island

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Light propagation through alignment-patterned liquid crystal gratings

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MOLECULAR CRYSTALS AND LIQUID CRYSTALS 2002年第1期375卷 491-500页

作者： Scharf, T Bohley, C Univ Neuchatel Inst Microtechnol CH-2000 Neuchatel Switzerland

We analysed the light propagation through alignment-patterned liquid crystal films where the alignment is planar and homeotropic for different domains, respectively. Using elastic theory the nematic director field can be analytically calculated with the method of conformal mapping in the one elastic constant approximation. A smooth change of the nematic director field is found with defect points at the substrate surfaces. In order to investigate the propagation of light passing through such a liquid crystalline thin film with spatially varying birefringence, we use a rigorous method. The use of rigorous methods allows the simulation of the time-dependent electric and magnetic fields for a region that is two-dimensional and possibly anisotropic. Simulations are made by the finite-difference time-domain method (FDTD), which is a numerical approach for the rigorous solution of the Maxwell equations. This method, in contrast to methods of geometrical and matrix optics, delivers results which include diffraction and scattering.

关键词： liquid crystal gratings anisotropic gradient index media light propagation finite-difference time-domain method

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Mechanisms for enhancing power throughput from planar nano-apertures for near-field optical data storage

Mechanisms for enhancing power throughput from planar nano-a...

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International Symposium on Optical Memory (ISOM2001)

作者： Shi, XL Hesselink, L Stanford Univ Dept Elect Engn Palo Alto CA 94305 USA

Near-field optical data storage systems are important for ultrahigh density data storage. One type of near-field optical data Storage system uses a planar nano-aperture to define the data storage resolution. However, conventional nano-apertures have a tradeoff between resolution and power throughput. Recently, we reported a novel "C"-aperture design to overcome this problem. In this paper, we present our study on the mechanisms for power throughput enhancement, based on a detailed study of nano-slits using numerical simulations. We find that generating a propagation mode is essential for high power throughput, and by optimizing the design of the aperture thickness, resonant transmission can be achieved for even higher power throughput.

关键词： nano-aperture nano-slits near-field optics finite-difference time-domain method power throughput "C"-aperture mechanism

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Unit cell approach to full-wave analysis of meander delay line using FDTD periodic structure Modeling method

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IEEE TRANSACTIONS ON ADVANCED PACKAGING 2002年第2期25卷 215-222页

作者： Lee, H Kim, J Korea Adv Inst Sci & Technol Dept Elect Engn & Comp Sci Terahertz Media & Syst Lab Taejon 305701 South Korea

Unit cell modeling is performed to determine the effect of electromagnetic coupling on the propagation characteristics of a meander delay line, which is widely used in printed circuit boards and packages. Since the design of a delay line must guarantee a several tens of picosecond timing margin in modern highspeed packages and board level interconnections, a penetrating understanding of the meander effect is essential. The propagation delay, the characteristic impedance, and the stop-band characteristic of the meander delay line have been carefully investigated based on a full-wave analysis using the finite-difference time-domain (FDTD) periodic structure modeling method. The periodicity of the meander line is utilized based on Floquet's theorem, resulting in a reduction of the computational domain in the FDTD simulation and providing a unit cell model of the meander line. The unit cell modeling of the meander delay line shows the effect of electromagnetic coupling in meander line structure on the reduction of the propagation delay. Also, an analysis based on the unit cell modeling was confirmed by time-domain reflection/transmission measurements. To investigate the effects of variation of substrate thickness (H) and trace width (W) generated during the manufacturing process, the propagation delay and the characteristic impedance were analyzed with different values of H and W. The unit cell modeling approach based on Floquet's propagation mode analysis produces a transmission line model of the meander delay line, which gives the dispersion relation and the characteristic impedance. This work should prove useful for high-speed digital circuit board designers.

关键词： delay line finite-difference time-domain method meander periodic structure signal integrity

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