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排序方式: 共有237条查询结果,搜索用时 15 毫秒
1.
Single-polarization single-mode photonic crystal fibers 总被引:5,自引:0,他引:5
K. Saitoh M. Koshiba 《Photonics Technology Letters, IEEE》2003,15(10):1384-1386
A new structure of single-polarization single-mode (SPSM) photonic crystal fiber (PCF) is proposed and analyzed by using a full-vector finite element method with anisotropic perfectly matched layers. From the numerical results it is confirmed that the proposed fiber is low-loss SPSM-PCF within the wavelengths ranging from 1.48 to 1.6 /spl mu/m, where only the slow-axis mode exists and the confinement loss is less than 0.1 dB/km. 相似文献
2.
A beam propagation method (BPM) based on the finite element method (FEM) is described for longitudinally varying three-dimensional (3-D) optical waveguides. In order to avoid nonphysical reflections from the computational window edges, the transparent boundary condition is introduced. The present algorithm using the Pade approximation is, to our knowledge, the first wide-angle finite element beam propagation method for 3-D waveguide structures. To show the validity and usefulness of this approach, numerical results are shown for Gaussian-beam excitation of a straight rib waveguide and guided-mode propagation in a Y-branching rib waveguide 相似文献
3.
Modeling of photonic crystal structures is an ongoing challenge. This letter is devoted to the theoretical modeling of photonic crystal resonant cavities, composed of elliptically shaped dielectric pillars. Through this rigorous study, we can examine the impact of the elliptical-shape deformations to important quantities related to the photonic crystal cavity performance, such as the quality factor and the resonance frequency. 相似文献
4.
Y. Nakamura Ichiro Tanaka N. Takeuchi S. Koshiba H. Sakaki 《Journal of Electronic Materials》1998,27(11):1240-1243
We studied morphology of GaAs surfaces and the transport properties of two-dimensional electron gas (2DEG) on vicinal (111)B
planes. Multi-atomic steps (MASs) are found on the vicinal (111)B facet grown by molecular beam epitaxy, which will affect
electron transport on the facet. We also studied how the morphology of GaAs epilayers on vicinal (111)B substrates depends
on growth conditions, especially on the As4 flux. The uniformity of MASs on the substrates have been improved and smooth surfaces were obtained when the GaAs was grown
with high As4 flux, providing step periodicity of 20 nm. The channel resistance of the 2DEG perpendicular to the MASs is reduced drastically
with this smooth morphology. These findings are valuable not only for fabricating quantum devices on the (111)B facets but
also those on the vicinal (111)B substrates. 相似文献
5.
The finite element method (FEM) with the high-order mixed-interpolation-type triangular element is used to solve the problem of practical microstrip lines with arbitrary metallization cross section. Analyses are carried out to produce the frequency characteristics of propagation constant, characteristic impedance, and attenuation constant of shielded microstrip lines with rectangular, trapezoidal, and semi-trapezoidal strip cross sections. A comparison of the numerical results with those of the existing results shows good agreement and thus verifies the versatility of the FEM. Also, the numerical results show the effects of the metallization cross sections on the transmission properties and thus emphasize the importance of considering the practical microstrip configurations in the design of miniaturized MMICs 相似文献
6.
7.
Prof. Mitsunobu Nakamura Dr. Tadao Takada Prof. Kazushige Yamana 《Chembiochem : a European journal of chemical biology》2019,20(23):2949-2954
B- to Z-DNA transitions play a crucial role in biological systems and have attracted the interest of researchers for their applications in DNA nanotechnology. DNA and DNA analogues have also been used as templates to construct helical chromophore associations with π interactions. In this work, the B- to Z-DNA transition-induced switching of pyrene in an association manner was evaluated using DNA duplexes with non-nucleosidic pyrene residues in the middle of d(CG) repeat sequences. One of the pyrene-labeled DNAs was shown to exhibit inverted exciton coupled circular dichroism signals upon pyrene association through a B- to Z-DNA transition. This observation indicates that pyrene association switches the DNA conformation from right- to left-handed. Interestingly, the fluorescence of the pyrene-labeled DNA duplex also dynamically changed upon switching of the pyrene in an association-based manner. Taken together, these studies demonstrate that pyrene-labeled DNA shows promise as a chiroptical molecular switch. 相似文献
8.
A measurement method for an unsteady temperature field by using a Mach-Zehnder interferometer and image processing technique is presented. In this study, the results measured by this method were compared with the calculated results under Reynolds numbers (Re = UL/v) ranging to less than 350 in the steady-state. The unsteady characteristics of the local Nusselt numbers (Nux = αxL/λ) around an elastically vibrating plate were investigated under the conditions that the reduced frequency (N = 1/Ro) ranged from 4.8 to 8.6 and the amplitude of vibration was kept small relative to the plate length. In this study it was clarified that the distributions of the Local Nusselt numbers were observed flutteringly, and that the phase of the time-averaged Nusselt number is delayed compared to the phase of the velocity at the trailing edge. These results indicate that the enhancement of the time-averaged heat transfer coefficient around the vibrating plate depended on the Rossby number. © 1997 Scripta Technica. Inc. Heat Trans Jpn Res. 25 (2): 88–102, 1996 相似文献
9.
DNA‐Templated Synthesis of Perylenediimide Stacks Utilizing Abasic Sites as Binding Pockets and Reactive Sites 下载免费PDF全文
Dr. Tadao Takada Misa Ido Akane Ashida Dr. Mitsunobu Nakamura Prof. Kazushige Yamana 《Chembiochem : a European journal of chemical biology》2016,17(23):2230-2233
DNA is considered to be a promising biomolecule as a template and scaffold for arranging and organizing functional molecules on the nanoscale. The construction and evaluation of DNAs containing multiple functional molecules that are useful for optoelectronic devices and sensors has been studied. In this paper we report the efficient incorporation of perylenediimide (PDI) units into DNA by using abasic sites both as binding sites and as reactive sites and the construction of PDI stacks within the DNA structure, accomplished through the preorganization of the PDI units in the hydrophobic pocket within the DNA. Our approach could become a valuable method for construction of DNA/chromophore hybrid structures potentially useful for the design of DNA‐based devices and biosensors. 相似文献
10.
Mitsunobu Kawano Toshiaki Matsui Ryuji Kikuchi Hiroyuki Yoshida Toru Inagaki Koichi Eguchi 《Journal of power sources》2008
Direct internal and external reforming operations on Ni-samaria-doped ceria (SDC) anode with the practical size solid oxide fuel cell (SOFC) at intermediate temperatures from 600 to 750 °C are carried out to reveal the reforming activities and the electrochemical activities, being compared with the hydrogen-fueled power generation. The cell performance with direct internal and external steam reforming of methane and their limiting current densities were almost the same irrespective of the progress of reaction in the methane reformate at 700 and 750 °C. The durability test for 5.5 h at 750 °C with direct internal reforming operation confirmed that the cell performance did not deteriorate. The operation temperature of the cell controlled the reforming activities on the anode, and the large size electrode gave rise to high conversion due to the slow space velocity of the steam reforming. Direct internal steam reforming attained sufficient level of conversion for SOFC power generation with methane at 700 and 750 °C on the large Ni-SDC cermet anode. 相似文献