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47 results on '"Takeda, Mitsuo Wada"'

1. Anisotropic Babinet-invertible metasurfaces to realize transmission-reflection switching for orthogonal polarizations of light

Author

Nakata, Yosuke, Urade, Yoshiro, Okimura, Kunio, Nakanishi, Toshihiro, Miyamaru, Fumiaki, Takeda, Mitsuo Wada, and Kitano, Masao

Subjects
Physics - Optics
Abstract

The electromagnetic properties of an extremely thin metallic checkerboard drastically change from resonant reflection (transmission) to resonant transmission (reflection) when the local electrical conductivity at the interconnection points of the checkerboard is switched. To date, such critical transitions of metasurfaces have been applied only when they have 4-fold rotational symmetry, and their application to polarization control, which requires anisotropy, has been unexplored. To overcome this applicability limitation and open up new pathways for dynamic deep-subwavelength polarization control by utilizing critical transitions of checkerboard-like metasurfaces, we introduce a universal class of anisotropic Babinet-invertible metasurfaces enabling transmission-reflection switching for each orthogonally polarized wave. As an application of anisotropic Babinet-invertible metasurfaces, we experimentally realize a reconfigurable terahertz polarizer whose transmitting axis can be dynamically rotated by $90^\circ$., Comment: 7 pages, 7 figures; the metadata is fixed

Published
2016
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2. Supersymmetric correspondence in spectra on a graph and its line graph: From circuit theory to spoof plasmons on metallic lattices

Author

Nakata, Yosuke, Urade, Yoshiro, Nakanishi, Toshihiro, Miyamaru, Fumiaki, Takeda, Mitsuo Wada, and Kitano, Masao

Subjects
Physics - Optics
Abstract

We investigate the supersymmetry (SUSY) structures for inductor-capacitor circuit networks on a simple regular graph and its line graph. We show that their eigenspectra must coincide (except, possibly, for the highest eigenfrequency) due to SUSY, which is derived from the topological nature of the circuits. To observe this spectra correspondence in the high-frequency range, we study spoof plasmons on metallic hexagonal and kagom\'e lattices. The band correspondence between them is predicted by a simulation. Using terahertz time-domain spectroscopy, we demonstrate the band correspondence of fabricated metallic hexagonal and kagom\'e lattices., Comment: 9 pages, 8 figures

Published
2016
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3. Terahertz Time-Domain Spectroscopy

Author

Nishizawa, Seizi, Sakai, Kiyomi, Hangyo, Masanoi, Nagashima, Takeshi, Takeda, Mitsuo Wada, Tominaga, Keisuke, Oka, Asako, Tanaka, Koichiro, Morikawa, Osamu, Ascheron, Claus E., editor, Kölsch, Hans J., editor, Skolaut, Werner, editor, and Sakai, Kiyomi, editor

Published
2005
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15. Terahertz radiation from meta-atom-loaded photoconductive antennas

Author

Takano, Keisuke, Nishida, T., Kang, Boyoung, Sasaki, H., Miyamaru, F., Takeda, Mitsuo Wada, Padilla, Willie J., Hangyo, M., Akalin, Tahsin, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), and Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)

Subjects
[SPI]Engineering Sciences [physics]
Abstract

International audience

Published
2013

16. [Invited] Terahertz radiation from meta-atom-loaded photoconductive antennas

Author

Takano, Keisuke, Nishida, T., Kang, Boyoung, Sasaki, H., Miyamaru, F., Takeda, Mitsuo Wada, Padilla, Willie J., Hangyo, M., Akalin, Tahsin, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), and Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)

Subjects
[SPI]Engineering Sciences [physics]
Published
2013

18. Coupling between localized resonance and excitation of surface waves in metal hole arrays

Author

Miyamaru, Fumiaki; HVSNOakh, Takeda, Mitsuo Wada; gmkVPVAU, Miyamaru, Fumiaki; HVSNOakh, and Takeda, Mitsuo Wada; gmkVPVAU

Abstract

We investigate the transition of the dominant resonant transmission mechanism from localized resonance to excitation of surface waves and vice versa in metal hole arrays. The transition occurs continuously with a change in the length of the rectangular holes. We also study the effect of the incident-beam diameter and surface condition on the transmission spectrum. Our experimental results show the important differences between the two mechanisms. They also confirm the theoretical prediction of Bravo-Abad [Phys. Rev. B 76, 241102(R) (2007)].

Published
2013

19. Characteristics and generation process of surface waves excited on a perfect conductor surface

Author

Miyamaru, Fumiaki; HVSNOakh, Kamijyo, Mototsugu, Takano, Keisuke, Hangyo, Masanori, Miyazaki, Hiroshi, Takeda, Mitsuo Wada; gmkVPVAU, Miyamaru, Fumiaki; HVSNOakh, Kamijyo, Mototsugu, Takano, Keisuke, Hangyo, Masanori, Miyazaki, Hiroshi, and Takeda, Mitsuo Wada; gmkVPVAU

Abstract

We investigate characteristics and generation process of surface waves excited on a structured perfect conductor surface in order to clarify the mechanism of resonant transmission in metal hole arrays made of the perfect conductor. By using a metal hole array of kagome lattice, we can separate two modes excited on the perfect conductor surface; a surface wave and an edge mode. Our calculation based on finite-difference time-domain method provides a generation process of the edge mode and the surface wave that is responsible for the resonant transmission in metal hole arrays. (C) 2010 Optical Society of America, This paper was published in OPTICS EXPRESS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OE.18.017576 . Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.

Published
2012

20. Emission of Terahertz Radiations from Fractal Antennas

Author

Miyamaru, Fumiaki, Saito, Yu, Takeda, Mitsuo Wada, Liu, Liyu, Hou, Bo, Wen, Weijia, Sheng, Ping, Miyamaru, Fumiaki, Saito, Yu, Takeda, Mitsuo Wada, Liu, Liyu, Hou, Bo, Wen, Weijia, and Sheng, Ping

Abstract

We investigate the emission of terahertz radiation from a photoconductive fractal antenna fabricated on a semi-insulating gallium arsenide substrate. Owing to the self-similarity of fractal structures, our fractal antenna shows a multiband emission of terahertz radiation. The emission intensity at peak frequency is about twice that from a bow-tie antenna. We also investigate the mechanism of the multiband emission by using the finite-difference time-domain calculation.

Published
2009

21. Terahertz Electric Response of Fractal Metamaterial Structures

Author

Miyamaru, Fumiaki, Saito, Yu, Takeda, Mitsuo Wada, Hou, Bo, Liu, Liyu, Wen, Weijia, Sheng, Ping, Miyamaru, Fumiaki, Saito, Yu, Takeda, Mitsuo Wada, Hou, Bo, Liu, Liyu, Wen, Weijia, and Sheng, Ping

Abstract

The electromagnetic response of H-fractal structures, consisting of self-similar metallic lines or slits in metallic films deposited on silicon substrate, has been investigated in the terahertz region. The subwavelength fractal structure was observed to display electric resonances, with redshift in the resonant frequencies accompanying an increase in either the fractal level or the sample size. The associated increase in sample size is several times smaller than that expected from the scaling rule, indicating the possibility for achieving significantly subwavelength resonances. The very strong terahertz wave confinement in subwavelength regions (about 17 times smaller than the wavelength in vacuum), together with the multifrequency nature of the fractal resonances, characterize our metamaterial unit cell. By measuring both the power transmission and phase shift, we obtain the real and imaginary parts of the effective permittivity for our H-fractal structures in the terahertz regime. Strongly dispersive behavior of the real part of the permittivity is seen at multiple frequencies.

Published
2008

41. Terahertz Time-Domain Spectroscopy.

Author

Ascheron, Claus E., Kölsch, Hans J., Skolaut, Werner, Nishizawa, Seizi, Sakai, Kiyomi, Hangyo, Masanoi, Nagashima, Takeshi, Takeda, Mitsuo Wada, Tominaga, Keisuke, Oka, Asako, Tanaka, Koichiro, and Morikawa, Osamu

Abstract

Terahertz time-domain spectroscopy (THz-TDS) is one of the most successful fields of THz optoelectronics. Measurements of semiconductors, ferroelectric crystals of current industrial interest, photonic crystals and biomolecules by means of standard THz-TDS are shown first, then modified versions such as attenuated total reflection spectroscopy and ellipsometry are described. In addition to the THz-TDS, generation and detection of THz radiation with the use of multimode laser diodes and applications in spectroscopy are described, although the radiation is emitted in CW mode. This Chapter is composed of topical sections written by specialists of the respective topics. [ABSTRACT FROM AUTHOR]

Published
2005
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43. Complex Phonon-Polariton Dispersion of Congruent Lithium Niobate Studied by THz Time-Domain Spectroscopy.

Author

Kojima, Seiji, Nishizawa, Seizi, Kitahara, Hideaki, and Takeda, Mitsuo Wada

Subjects
LITHIUM niobate, DISPERSION (Chemistry), PHONONS, POLARITONS, SPECTRUM analysis, LITHIUM compounds
Abstract

Complex polariton dispersion relations were determined in the congruent lithium niobate crystal using the latest terahertz time domain spectroscopy. We measured the power and phase transmission spectra by the coherent THz radiation. The complex dispersion relations of phonon polariton frequency and damping have been investigated simply by rotating the polarization plane of an incident beam. These dispersive properties have been consistently reproduced by the damped harmonic oscillator model related to the lowest frequency infrared active modes. [ABSTRACT FROM AUTHOR]

Published
2005
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44. Smart Processing Development of Photonic Crystals and Fractals.

Author

Miyamoto, Yoshinari, Kirihara, Soshu, Kanehira, Shingo, Takeda, Mitsuo Wada, Honda, Katsuya, and Sakoda, Kazuaki

Subjects
TRANSMISSION of electromagnetic waves, FRACTALS, CRYSTALLOGRAPHY, CRYSTALS, POWDERS, ELECTROMAGNETIC theory, ELECTROMAGNETIC waves, CONSTRUCTION materials
Abstract

A new concept of smart processing is proposed that can produce advanced materials and components by finely controlling processing energy and engineering structures. New functional components of 3D photonic crystals and fractals are demonstrated, which are constructed of dielectric ceramics and a polymer using a CAD/CAM stereolithography system. By modifying the structure of diamond-like photonic crystals using free-form fabrication, electromagnetic waves can be controlled, opening the way for new applications in communication and sensing technology. The photonic fractal, a new material that can strongly localize electromagnetic waves without reflection and transmission, will also lead to new applications in the energy and medical fields. [ABSTRACT FROM AUTHOR]

Published
2004
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45. Group-Velocity Anomaly Modes in Hybrid Bands of Photonic Crystals Made of Ferroelectrics

Author

Takeda, Mitsuo Wada, Arikawa, Akihiko, Araki, Ryohei, Nakata, Yosuke, Miyamaru, Fumiaki, and Yamaguchi, Toshihisa

Abstract

In photonic crystals composed of ferroelectrics, the hybrid bands with corresponding to new additional band gaps are expected to appear around the Brillouin zone’s center and boundaries. In this hybrid bands, the group-velocity anomaly modes related to the phonon-polariton branches are expected to be discovered. Propagation characteristics of the group-velocity anomaly modes in the hybrid bands of one-dimensional photonic crystals fabricated by ferroelectric Li2Ge7O15 single crystals are discussed on the basis of finite element method and finite-difference time-domain numerical analyses and experimental results obtained by terahertz time-domain spectroscopy. It is founded that the electric-field intensity of the standing-wave mode at the end point of the dielectric band branch is found to be localized around all of the ferroelectrics plates in the photonic crystal. In contrast, group-velocity anomaly mode in the vicinity of the standing-wave mode is strongly localized around the first ferroelectrics plate on the incident side and decays as it propagates through the following ferroelectrics plates.

Published
2006
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46. Localization of Electromagnetic Wave in 3D Periodic and Fractal Structures

Author

Miyamoto, Yoshinari, Kirihara, Soshu, and Takeda, Mitsuo Wada

Abstract

Localization or confinement of electromagnetic or optical waves is reviewed briefly in respect to the wave interaction with the specific structures of periodic, random, and fractal (self-similar) geometries, which can enhance strong interference, scattering, and resonance of waves. The localization of microwave in photonic crystals with diamond structure and in photonic fractals with Menger sponge structure of dielectric media is reported and discussed about the difference of localization behaviors. These 3D structures are fabricated easily from liquid photosensitive resins or ceramic dispersed ones by a CAD/CAM stereolithography. The localization in photonic fractals is supported with several measurements of transmission, 90° wave scattering, electric field intensity profile, and FDTD (finite-difference time-domain) simulation for localized modes. An empirical equation to predict the localization frequencies shows good agreements with measured results as well. The localization in a photonic crystal can be explained by Bragg scattering, while that in a photonic fractal by resonance in the fractal cavity.

Published
2006
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47. Characterization of Terahertz Metamaterials Fabricated on Flexible Plastic Films: Toward Fabrication of Bulk Metamaterials in Terahertz Region.

Author

Miyamaru, Fumiaki, Takeda, Mitsuo Wada, and Taima, Kazuo

Abstract

Electromagnetic characteristics of a split-ring resonator (SRR) fabricated on flexible thin plastic films are investigated for the purpose of developing three-dimensional (3D) metamaterials in the terahertz region. Both electric and magnetic resonances are observed at frequencies determined by the structural parameters of the SRR. Since the optical path length of the plastic film is smaller than the wavelength of the resonant frequency of metamaterials, the diffraction effect is avoided in a 3D metamaterial. We also observe that each layer functions independently without interlayer interaction, indicating that the properties of the metamaterial are determined only by the unit cell design. [ABSTRACT FROM AUTHOR]

Published
2009
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