start-ver=1.4
cd-journal=joma
no-vol=15
cd-vols=
no-issue=
article-no=
start-page=
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2015
dt-pub=201509
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Metamaterial absorbers for infrared inspection technologies
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=
en-copyright=
kn-copyright=

en-aut-name=IshikawaAtsushi
en-aut-sei=Ishikawa
en-aut-mei=Atsushi
kn-aut-name=石川篤
kn-aut-sei=石川
kn-aut-mei=篤
aut-affil-num=1
ORCID=

affil-num=1
en-affil=
kn-affil=Department of Electrical and Electronic Engineering, Okayama University
END

start-ver=1.4
cd-journal=joma
no-vol=5
cd-vols=
no-issue=
article-no=
start-page=12570
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2015
dt-pub=2015
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Metamaterial Absorbers for Infrared Detection of Molecular Self-Assembled Monolayers
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=The emerging field of plasmonic metamaterials has introduced new degree of freedom to manipulate optical field from nano to macroscopic scale, offering an attractive platform for sensing applications. So far, metamaterial sensor concepts, however, have focused on hot-spot engineering to improve the near-field enhancement, rather than fully exploiting tailored material properties. Here, we present a novel spectroscopic technique based on the metamaterial infrared (IR) absorber allowing for a low-background detection scheme as well as significant plasmonic enhancement. Specifically, we experimentally demonstrate the resonant coupling of plasmonic modes of a metamaterial absorber and IR vibrational modes of a molecular self-assembled monolayer. The metamaterial consisting of an array of Au/MgF2/Au structures exhibits an anomalous absorption at ~3000 cm−1, which spectrally overlaps with C-H stretching vibrational modes. Symmetric/asymmetric C-H stretching modes of a 16-Mercaptohexadecanoic acid monolayer are clearly observed as Fano-like anti-resonance peaks within a broad plasmonic absorption of the metamaterial. Spectral analysis using Fano line-shape fitting reveals the underlying resonant interference in plasmon-molecular coupled systems. Our metamaterial approach achieves the attomole sensitivity with a large signal-to-noise ratio in the far-field measurement, thus may open up new avenues for realizing ultrasensitive IR inspection technologies.
en-copyright=
kn-copyright=

en-aut-name=IshikawaAtsushi
en-aut-sei=Ishikawa
en-aut-mei=Atsushi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=TanakaTakuo
en-aut-sei=Tanaka
en-aut-mei=Takuo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

affil-num=1
en-affil=
kn-affil=Department of Electrical and Electronic Engineering, Okayama University

affil-num=2
en-affil=
kn-affil=Metamaterials Laboratory, RIKEN
END

start-ver=1.4
cd-journal=joma
no-vol=111
cd-vols=
no-issue=18
article-no=
start-page=183102
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2017
dt-pub=20171030
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Selective electroless plating of 3D-printed plastic structures for three-dimensional microwave metamaterials
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract= A technique of selective electroless plating onto PLA-ABS (Polylactic Acid-Acrylonitrile Butadiene Styrene) composite structures fabricated by three-dimensional (3D) printing is demonstrated to construct 3D microwave metamaterials. The reducing activity of the PLA surface is selectively enhanced by the chemical modification involving Sn2+ in a simple wet process, thereby forming a highly conductive Ag-plated membrane only onto the PLA surface. The fabricated metamaterial composed of Ag-plated PLA and non-plated ABS parts is characterized experimentally and numerically to demonstrate the important bi-anisotropic microwave responses arising from the 3D nature of metallodielectric structures. Our approach based on a simple wet chemical process allows for the creation of highly complex 3D metal-insulator structures, thus paving the way toward the sophisticated microwave applications of the 3D printing technology. Published by AIP Publishing.
en-copyright=
kn-copyright=

en-aut-name=IshikawaAtsushi
en-aut-sei=Ishikawa
en-aut-mei=Atsushi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=KatoTaiki
en-aut-sei=Kato
en-aut-mei=Taiki
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=TakeyasuNobuyuki
en-aut-sei=Takeyasu
en-aut-mei=Nobuyuki
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=FujimoriKazuhiro
en-aut-sei=Fujimori
en-aut-mei=Kazuhiro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=TsurutaKenji
en-aut-sei=Tsuruta
en-aut-mei=Kenji
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

affil-num=1
en-affil=Department of Electrical and Electronic Engineering, Okayama University
kn-affil=

affil-num=2
en-affil=Department of Electrical and Electronic Engineering, Okayama University
kn-affil=

affil-num=3
en-affil=Department of Chemistry, Okayama University
kn-affil=

affil-num=4
en-affil=Department of Electrical and Electronic Engineering, Okayama University
kn-affil=

affil-num=5
en-affil=Department of Electrical and Electronic Engineering, Okayama University
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=111
cd-vols=
no-issue=24
article-no=
start-page=243106
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2017
dt-pub=20171211
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Robust plasmonic hot-spots in a metamaterial lattice for enhanced sensitivity of infrared molecular detection
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract= High-density and long-lived plasmonic hot-spots are an ideal system for high-sensitive surface-enhanced infrared absorption (SEIRA), but these conditions arc usually incompatible due to unwanted near-field coupling between the adjacent unit structures. Here, by fully controlling plasmonic interference in a metamaterial lattice, we experimentally demonstrate densely packed long-lived quadrupole plasmons for high-sensitive SEIRA. The metamaterial consists of a strongly coupled array of super-and sub-radiant plasmonic elements to exhibit an electromagnetic transparency mode at 1730 cm(-1), which spectrally overlaps with the C=O vibrational mode. In the SEIRA measurement, the C=O mode of poly(methyl methacrylate) molecules is clearly observed as a distinct dip within a transmission peak of the metamaterial. The corresponding numerical simulations reveal that constructive interference uniformly forms coherent quadrupole plasmons over the metamaterial lattice, leading to a stronger molecular signal from the system. Our metamaterial approach provides a robust way to construct ideal hot-spots over the sample, paving the way toward a reliable sensing platform of advanced infrared inspection technologies. Published by AIP Publishing.
en-copyright=
kn-copyright=

en-aut-name=IshikawaAtsushi
en-aut-sei=Ishikawa
en-aut-mei=Atsushi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=HaraShuhei
en-aut-sei=Hara
en-aut-mei=Shuhei
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=TanakaTakuo
en-aut-sei=Tanaka
en-aut-mei=Takuo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=ZhanXiang
en-aut-sei=Zhan
en-aut-mei=Xiang
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=TsurutaKenji
en-aut-sei=Tsuruta
en-aut-mei=Kenji
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

affil-num=1
en-affil=Department of Electrical and Electronic Engineering, Okayama University
kn-affil=

affil-num=2
en-affil=Department of Electrical and Electronic Engineering, Okayama University
kn-affil=

affil-num=3
en-affil=Metamaterials Laboratory, RIKEN
kn-affil=

affil-num=4
en-affil=NSF Nanoscale Science and Engineering Center, University of California
kn-affil=

affil-num=5
en-affil=Department of Electrical and Electronic Engineering, Okayama University
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=10
cd-vols=
no-issue=1
article-no=
start-page=6486
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2020
dt-pub=20200416
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Whitish daytime radiative cooling using diffuse reflection of non-resonant silica nanoshells
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Daytime radiative cooling offers efficient passive cooling of objects by tailoring their spectral responses, holding great promise for green photonics applications. A specular reflector has been utilized in cooling devices to minimize sunlight absorption, but such a glaring surface is visually less appealing, thus undesirable for public use. Here, by exploiting strong diffuse reflection of silica nanoshells in a polymer matrix, daytime radiative cooling below the ambient temperature is experimentally demonstrated, while showing whitish color under sunlight. The cooling device consists of a poly(methyl methacrylate) layer with randomly distributed silica nanoshells and a polydimethylsiloxane (PDMS) layer on an Ag mirror. The non-resonant nanoshells exhibit uniform diffuse reflection over the solar spectrum, while fully transparent for a selective thermal radiation from the underneath PDMS layer. In the temperature measurement under the sunlight irradiation, the device shows 2.3 degrees C cooler than the ambient, which is comparable to or even better than the conventional device without the nanoshells. Our approach provides a simple yet powerful nanophotonic structure for realizing a scalable and practical daytime radiative cooling device without a glaring reflective surface.
en-copyright=
kn-copyright=

en-aut-name=SuichiTakahiro
en-aut-sei=Suichi
en-aut-mei=Takahiro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=IshikawaAtsushi
en-aut-sei=Ishikawa
en-aut-mei=Atsushi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=TanakaTakuo
en-aut-sei=Tanaka
en-aut-mei=Takuo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=HayashiYasuhiko
en-aut-sei=Hayashi
en-aut-mei=Yasuhiko
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=TsurutaKenji
en-aut-sei=Tsuruta
en-aut-mei=Kenji
kn-aut-name=健二
kn-aut-sei=
kn-aut-mei=健二
aut-affil-num=5
ORCID=

affil-num=1
en-affil=Department of Electrical and Electronic Engineering, Okayama University
kn-affil=

affil-num=2
en-affil=Department of Electrical and Electronic Engineering, Okayama University
kn-affil=

affil-num=3
en-affil=Metamaterials Laboratory, RIKEN Cluster for Pioneering Research
kn-affil=

affil-num=4
en-affil=Department of Electrical and Electronic Engineering, Okayama University
kn-affil=

affil-num=5
en-affil=Department of Electrical and Electronic Engineering, Okayama University
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=117
cd-vols=
no-issue=10
article-no=
start-page=101103
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2020
dt-pub=20200909
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Super-chiral vibrational spectroscopy with metasurfaces for high-sensitive identification of alanine enantiomers
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Chiral nature of an enantiomer can be characterized by circular dichroism (CD) spectroscopy, but such a technique usually suffers from weak signal even with a sophisticated optical instrument. Recent demonstrations of plasmonic metasurfaces showed that chiroptical interaction of molecules can be engineered, thereby greatly simplifying a measurement system with high sensing capability. Here, by exploiting super-chiral field in a metasurface, we experimentally demonstrate high-sensitive vibrational CD spectroscopy of alanine enantiomers, the smallest chiral amino acid. Under linearly polarized excitation, the metasurface consisting of an array of staggered Au nano-rods selectively produces the left- and right-handed super-chiral fields at 1600 cm−1, which spectrally overlaps with the functional group vibrations of alanine. In the Fourier-transform infrared spectrometer measurements, the mirror symmetric CD spectra of D- and L-alanine are clearly observed depending on the handedness of the metasurface, realizing the reliable identification of small chiral molecules. The corresponding numerical simulations reveal the underlying resonant chiroptical interaction of plasmonic modes of the metasurface and vibrational modes of alanine. Our approach demonstrates a high-sensitive vibrational CD spectroscopic technique, opening up a reliable chiral sensing platform for advanced infrared inspection technologies.
en-copyright=
kn-copyright=

en-aut-name=IidaTakumi 
en-aut-sei=Iida
en-aut-mei=Takumi 
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=IshikawaAtsushi
en-aut-sei=Ishikawa
en-aut-mei=Atsushi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=TanakaTakuo
en-aut-sei=Tanaka
en-aut-mei=Takuo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=MuranakaAtsuya
en-aut-sei=Muranaka
en-aut-mei=Atsuya
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=UchiyamaMasanobu
en-aut-sei=Uchiyama
en-aut-mei=Masanobu
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=HayashiYasuhiko
en-aut-sei=Hayashi
en-aut-mei=Yasuhiko
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

en-aut-name=TsurutaKenji
en-aut-sei=Tsuruta
en-aut-mei=Kenji
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=7
ORCID=

affil-num=1
en-affil=Department of Electrical and Electronic Engineering, Okayama University
kn-affil=

affil-num=2
en-affil=Department of Electrical and Electronic Engineering, Okayama University
kn-affil=

affil-num=3
en-affil=Metamaterials Laboratory, RIKEN Cluster for Pioneering Research
kn-affil=

affil-num=4
en-affil=Advanced Elements Chemistry Laboratory, RIKEN Cluster for Pioneering Research
kn-affil=

affil-num=5
en-affil=Advanced Elements Chemistry Laboratory, RIKEN Cluster for Pioneering Research
kn-affil=

affil-num=6
en-affil=Department of Electrical and Electronic Engineering, Okayama University
kn-affil=

affil-num=7
en-affil=Department of Electrical and Electronic Engineering, Okayama University
kn-affil=
END