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1176 KiB

Open AccessFeature PaperCommunication

Magnetic Properties of Fibonacci-Modulated Fe-Au Multilayer Metamaterials

by Tomomi Suwa, Satoshi Tomita, Nobuyoshi Hosoito and Hisao Yanagi

Materials 2017, 10(10), 1209; https://doi.org/10.3390/ma10101209 - 20 Oct 2017

Cited by 7 | Viewed by 4972

Herein we experimentally study magnetic multilayer metamaterials with broken translational symmetry. Epitaxially-grown iron-gold (Fe-Au) multilayers modulated using Fibonacci sequence—referred to as magnetic inverse Fibonacci-modulated multilayers (IFMs)—are prepared using ultra-high-vacuum vapor deposition. Experimental results of in-situ reflection high-energy electron diffraction, magnetization curves, and ferromagnetic [...] Read more.

Herein we experimentally study magnetic multilayer metamaterials with broken translational symmetry. Epitaxially-grown iron-gold (Fe-Au) multilayers modulated using Fibonacci sequence—referred to as magnetic inverse Fibonacci-modulated multilayers (IFMs)—are prepared using ultra-high-vacuum vapor deposition. Experimental results of in-situ reflection high-energy electron diffraction, magnetization curves, and ferromagnetic resonance demonstrate that the epitaxially-grown Fe-Au IFMs have quasi-isotropic magnetization, in contrast to the in-plane magnetization easy axis in the periodic multilayers. Full article

(This article belongs to the Special Issue Advance in Plasmonics and Metamaterials)

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10447 KiB

Open AccessFeature PaperArticle

Enhanced Plasmonic Wavelength Selective Infrared Emission Combined with Microheater

by Hiroki Ishihara, Katsuya Masuno, Makoto Ishii, Shinya Kumagai and Minoru Sasaki

Materials 2017, 10(9), 1085; https://doi.org/10.3390/ma10091085 - 14 Sep 2017

Cited by 2 | Viewed by 4522

Abstract

The indirect wavelength selective thermal emitter that we have proposed is constructed using a new microheater, demonstrating the enhancement of the emission peak generated by the surface plasmon polariton. The thermal isolation is improved using a 2 μm-thick Si membrane having 3.6 and [...] Read more.

The indirect wavelength selective thermal emitter that we have proposed is constructed using a new microheater, demonstrating the enhancement of the emission peak generated by the surface plasmon polariton. The thermal isolation is improved using a 2 μm-thick Si membrane having 3.6 and 5.4 mm outer diameter. The emission at around the wavelength of the absorption band of CO₂ gas is enhanced. The absorption signal increases, confirming the suitability for gas sensing. Against input power, the intensity at the peak wavelength shows a steeper increasing ratio than the background intensity. The microheater with higher thermal isolation gives larger peak intensity and its increasing ratio against the input power. Full article

(This article belongs to the Special Issue Advance in Plasmonics and Metamaterials)

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1536 KiB

Open AccessFeature PaperArticle

Optimal Structure of a Plasmonic Chip for Sensitive Bio-Detection with the Grating-Coupled Surface Plasmon-Field Enhanced Fluorescence (GC-SPF)

by Keiko Tawa, Takuya Nakayama and Kenji Kintaka

Materials 2017, 10(9), 1063; https://doi.org/10.3390/ma10091063 - 11 Sep 2017

Cited by 14 | Viewed by 4330

Abstract

Surface plasmon field-enhanced fluorescence (SPF) has been one of the powerful tools for biosensors and bioimaging. A wavelength-scale periodic structure coated with a thin metal film is called a plasmonic chip, and it can provide SPF. SPF of Cy5-streptavidin (Cy5-SA) was measured on [...] Read more.

Surface plasmon field-enhanced fluorescence (SPF) has been one of the powerful tools for biosensors and bioimaging. A wavelength-scale periodic structure coated with a thin metal film is called a plasmonic chip, and it can provide SPF. SPF of Cy5-streptavidin (Cy5-SA) was measured on a biotinylated plasmonic chip with a grating of 480 nm-pitch. The optimal structure of a plasmonic sensor-chip was designed for improving detection sensitivity. The silver film thickness dependence of the SPF intensity was measured under the irradiation of the top panel of a sensor chip. Furthermore, the dependence of the SPF intensity on the distance from the metal surface was also investigated. The optimal structure for the largest fluorescence enhancement factor was 150 nm-thick silver and 10 nm-thick SiO₂ layers due to the enhanced electric field (excitation field), the surface plasmon coupled emission (SPCE), and the interference effect with reflected light. The largest enhancement factor was found to be 170-fold. Furthermore, not only the largest fluorescence intensity but also stable lower background noise were found to be essential for higher-sensitive detection. Full article

(This article belongs to the Special Issue Advance in Plasmonics and Metamaterials)

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2717 KiB

Open AccessArticle

Spectral Selectivity of Plasmonic Interactions between Individual Up-Converting Nanocrystals and Spherical Gold Nanoparticles

by Dawid Piątkowski, Mikołaj K. Schmidt, Magdalena Twardowska, Marcin Nyk, Javier Aizpurua and Sebastian Maćkowski

Materials 2017, 10(8), 905; https://doi.org/10.3390/ma10080905 - 04 Aug 2017

Cited by 3 | Viewed by 4039

Abstract

We experimentally demonstrate strong spectral selectivity of plasmonic interaction that occurs between α-NaYF₄:Er³⁺/Yb³⁺ nanocrystals, which feature two emission bands, and spherical gold nanoparticles, with plasmon frequency resonant with one of the emission bands. Spatially–resolved luminescence intensity maps acquired [...] Read more.

We experimentally demonstrate strong spectral selectivity of plasmonic interaction that occurs between α-NaYF₄:Er³⁺/Yb³⁺ nanocrystals, which feature two emission bands, and spherical gold nanoparticles, with plasmon frequency resonant with one of the emission bands. Spatially–resolved luminescence intensity maps acquired for individual nanocrystals, together with microsecond luminescence lifetime images, show two qualitatively different effects that result from the coupling between plasmon excitations in metallic nanoparticles and emitting states of the nanocrystals. On the one hand, we observe nanocrystals, whose emission intensity is strongly enhanced for both resonant and non-resonant bands with respect to the plasmon resonance. Importantly, this increase is accompanied with shortening of luminescence decays times. In contrast, a significant number of nanocrystals exhibits almost complete quenching of the emission resonant with the plasmon resonance of gold nanoparticles. Theoretical analysis indicates that such an effect can occur for emitters placed at distances of about 5 nm from gold nanoparticles. While under these conditions, both transitions experience significant increases of the radiative emission rates due to the Purcell effect, the non-radiative energy transfer between resonant bands results in strong quenching, which in that situation nullifies the enhancement. Full article

(This article belongs to the Special Issue Advance in Plasmonics and Metamaterials)

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1551 KiB

Open AccessArticle

Mie-Metamaterials-Based Thermal Emitter for Near-Field Thermophotovoltaic Systems

by Alok Ghanekar, Yanpei Tian, Sinong Zhang, Yali Cui and Yi Zheng

Materials 2017, 10(8), 885; https://doi.org/10.3390/ma10080885 - 31 Jul 2017

Cited by 24 | Viewed by 5057

Abstract

In this work, we theoretically analyze the performance characteristics of a near-field thermophotovoltaic system consisting a Mie-metamaterial emitter and GaSb-based photovoltaic cell at separations less than the thermal wavelength. The emitter consists of a tungsten nanoparticle-embedded thin film of SiO

_{2}

deposited on [...] Read more.

In this work, we theoretically analyze the performance characteristics of a near-field thermophotovoltaic system consisting a Mie-metamaterial emitter and GaSb-based photovoltaic cell at separations less than the thermal wavelength. The emitter consists of a tungsten nanoparticle-embedded thin film of SiO

_{2}

deposited on bulk tungsten. Numerical results presented here are obtained using formulae derived from dyadic Green’s function formalism and Maxwell–Garnett-Mie theory. We show that via the inclusion of tungsten nanoparticles, the thin layer of SiO

_{2}

acts like an effective medium that enhances selective radiative heat transfer for the photons above the band gap of GaSb. We analyze thermophotovoltaic (TPV) performance for various volume fractions of tungsten nanoparticles and thicknesses of SiO

_{2}

. Full article

(This article belongs to the Special Issue Advance in Plasmonics and Metamaterials)

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6855 KiB

Open AccessArticle

Thermal Stability of P-Type BiSbTe Alloys Prepared by Melt Spinning and Rapid Sintering

by Yun Zheng, Gangjian Tan, Yubo Luo, Xianli Su, Yonggao Yan and Xinfeng Tang

Materials 2017, 10(6), 617; https://doi.org/10.3390/ma10060617 - 06 Jun 2017

Cited by 19 | Viewed by 4687

Abstract

P-type BiSbTe alloys have been widely implemented in waste heat recovery from low-grade heat sources below 600 K, which may involve assorted environments and conditions, such as long-term service, high-temperature exposure (generally 473–573 K) and mechanical forces. It is important to evaluate the [...] Read more.

P-type BiSbTe alloys have been widely implemented in waste heat recovery from low-grade heat sources below 600 K, which may involve assorted environments and conditions, such as long-term service, high-temperature exposure (generally 473–573 K) and mechanical forces. It is important to evaluate the service performance of these materials in order to prevent possible failures in advance and extend the life cycle. In this study, p-type Bi_0.5Sb_1.5Te₃ commercial zone-melting (ZM) ingots were processed by melt spinning and subsequent plasma-activated sintering (MS-PAS), and were then subjected to vacuum-annealing at 473 and 573 K, respectively, for one week. The results show that MS-PAS samples exhibit excellent thermal stability when annealed at 473 K. However, thermal annealing at 573 K for MS-PAS specimens leads to the distinct sublimation of the element Te, which degrades the hole concentration remarkably and results in inferior thermoelectric performance. Furthermore, MS-PAS samples annealed at 473 K demonstrate a slight enhancement in flexural and compressive strengths, probably due to the reduction of residual stress induced during the sintering process. The current work guides the reliable application of p-type Bi_0.5Sb_1.5Te₃ compounds prepared by the MS-PAS technique. Full article

(This article belongs to the Special Issue Advance in Plasmonics and Metamaterials)

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Review

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17088 KiB

Open AccessReview

Metasurfaces Based on Phase-Change Material as a Reconfigurable Platform for Multifunctional Devices

by Niloufar Raeis-Hosseini and Junsuk Rho

Materials 2017, 10(9), 1046; https://doi.org/10.3390/ma10091046 - 06 Sep 2017

Cited by 123 | Viewed by 15709

Abstract

Integration of phase-change materials (PCMs) into electrical/optical circuits has initiated extensive innovation for applications of metamaterials (MMs) including rewritable optical data storage, metasurfaces, and optoelectronic devices. PCMs have been studied deeply due to their reversible phase transition, high endurance, switching speed, and data [...] Read more.

Integration of phase-change materials (PCMs) into electrical/optical circuits has initiated extensive innovation for applications of metamaterials (MMs) including rewritable optical data storage, metasurfaces, and optoelectronic devices. PCMs have been studied deeply due to their reversible phase transition, high endurance, switching speed, and data retention. Germanium-antimony-tellurium (GST) is a PCM that has amorphous and crystalline phases with distinct properties, is bistable and nonvolatile, and undergoes a reliable and reproducible phase transition in response to an optical or electrical stimulus; GST may therefore have applications in tunable photonic devices and optoelectronic circuits. In this progress article, we outline recent studies of GST and discuss its advantages and possible applications in reconfigurable metadevices. We also discuss outlooks for integration of GST in active nanophotonic metadevices. Full article

(This article belongs to the Special Issue Advance in Plasmonics and Metamaterials)

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5684 KiB

Open AccessFeature PaperReview

Metamaterial Waveguide Devices for Integrated Optics

by Tomohiro Amemiya, Toru Kanazawa, Satoshi Yamasaki and Shigehisa Arai

Materials 2017, 10(9), 1037; https://doi.org/10.3390/ma10091037 - 05 Sep 2017

Cited by 24 | Viewed by 6685

Abstract

We show the feasibility of controlling the magnetic permeability of optical semiconductor devices on InP-based photonic integration platforms. We have achieved the permeability control of GaInAsP/InP semiconductor waveguides by combining the waveguide with a metamaterial consisting of gate-controlled split ring resonators. The split-ring [...] Read more.

We show the feasibility of controlling the magnetic permeability of optical semiconductor devices on InP-based photonic integration platforms. We have achieved the permeability control of GaInAsP/InP semiconductor waveguides by combining the waveguide with a metamaterial consisting of gate-controlled split ring resonators. The split-ring resonators interact magnetically with light travelling in the waveguide and move the effective relative permeability of the waveguide away from 1 at optical frequencies. The variation in permeability can be controlled with the gate voltage. Using this variable-permeability waveguide, we have built an optical modulator consisting of a GaInAsP/InP Mach–Zehnder interferometer for use at an optical communication wavelength of 1.55 μm. The device changes the permeability of its waveguide arm with controlling gate voltage, thereby varying the refractive index of the arm to modulate the intensity of light. For the study of variable-permeability waveguide devices, we also propose a method of extracting separately the permittivity and permeability values of devices from the experimental data of light transmission. Adjusting the permeability of optical semiconductors to the needs of device designers will open the promising field of ‘permeability engineering’. Permeability engineering will facilitate the manipulation of light and the management of photons, thereby contributing to the development of novel devices with sophisticated functions for photonic integration. Full article

(This article belongs to the Special Issue Advance in Plasmonics and Metamaterials)

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4739 KiB

Open AccessReview

Artificial Structural Color Pixels: A Review

by Yuqian Zhao, Yong Zhao, Sheng Hu, Jiangtao Lv, Yu Ying, Gediminas Gervinskas and Guangyuan Si

Materials 2017, 10(8), 944; https://doi.org/10.3390/ma10080944 - 14 Aug 2017

Cited by 60 | Viewed by 11695

Abstract

Inspired by natural photonic structures (Morpho butterfly, for instance), researchers have demonstrated varying artificial color display devices using different designs. Photonic-crystal/plasmonic color filters have drawn increasing attention most recently. In this review article, we show the developing trend of artificial structural color pixels [...] Read more.

Inspired by natural photonic structures (Morpho butterfly, for instance), researchers have demonstrated varying artificial color display devices using different designs. Photonic-crystal/plasmonic color filters have drawn increasing attention most recently. In this review article, we show the developing trend of artificial structural color pixels from photonic crystals to plasmonic nanostructures. Such devices normally utilize the distinctive optical features of photonic/plasmon resonance, resulting in high compatibility with current display and imaging technologies. Moreover, dynamical color filtering devices are highly desirable because tunable optical components are critical for developing new optical platforms which can be integrated or combined with other existing imaging and display techniques. Thus, extensive promising potential applications have been triggered and enabled including more abundant functionalities in integrated optics and nanophotonics. Full article

(This article belongs to the Special Issue Advance in Plasmonics and Metamaterials)

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30055 KiB

Open AccessReview

Wavelength- or Polarization-Selective Thermal Infrared Detectors for Multi-Color or Polarimetric Imaging Using Plasmonics and Metamaterials

by Shinpei Ogawa and Masafumi Kimata

Materials 2017, 10(5), 493; https://doi.org/10.3390/ma10050493 - 04 May 2017

Cited by 65 | Viewed by 9573

Abstract

Wavelength- or polarization-selective thermal infrared (IR) detectors are promising for various novel applications such as fire detection, gas analysis, multi-color imaging, multi-channel detectors, recognition of artificial objects in a natural environment, and facial recognition. However, these functions require additional filters or polarizers, which [...] Read more.

Wavelength- or polarization-selective thermal infrared (IR) detectors are promising for various novel applications such as fire detection, gas analysis, multi-color imaging, multi-channel detectors, recognition of artificial objects in a natural environment, and facial recognition. However, these functions require additional filters or polarizers, which leads to high cost and technical difficulties related to integration of many different pixels in an array format. Plasmonic metamaterial absorbers (PMAs) can impart wavelength or polarization selectivity to conventional thermal IR detectors simply by controlling the surface geometry of the absorbers to produce surface plasmon resonances at designed wavelengths or polarizations. This enables integration of many different pixels in an array format without any filters or polarizers. We review our recent advances in wavelength- and polarization-selective thermal IR sensors using PMAs for multi-color or polarimetric imaging. The absorption mechanism defined by the surface structures is discussed for three types of PMAs—periodic crystals, metal-insulator-metal and mushroom-type PMAs—to demonstrate appropriate applications. Our wavelength- or polarization-selective uncooled IR sensors using various PMAs and multi-color image sensors are then described. Finally, high-performance mushroom-type PMAs are investigated. These advanced functional thermal IR detectors with wavelength or polarization selectivity will provide great benefits for a wide range of applications. Full article

(This article belongs to the Special Issue Advance in Plasmonics and Metamaterials)

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