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Your search keyword '"Lei, Dang Yuan"' showing total 237 results
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237 results on '"Lei, Dang Yuan"'

1. Experimental demonstration of light capsule embracing super-sized darkness inside via anti-resolution

Author

Wan, Chao, Huang, Kun, Han, Tiancheng, Leong, Eunice, Ding, Weiqiang, Yeo, Tat-Soon, Yu, Xia, Teng, Jinghua, Lei, Dang Yuan, Maier, Stefan A., Zhang, Shuang, and Qiu, Cheng-Wei

Subjects
Physics - Optics
Abstract

We theoretically and experimentally demonstrate the focusing of macroscopic 3D darkness surrounded by all light in free space. The object staying in the darkness is similar to staying in an empty light capsule because light just bypasses it by resorting to destructive interference. Its functionality of controlling the direction of energy flux of light macroscopically is fascinating, similar in some sense to the transformation-based cloaking effect. Binary-optical system exhibiting anti-resolution (AR) is designed and fabricated, by which electromagnetic energy flux avoids and bends smoothly around a nearly perfect darkness region. AR remains an unexplored topic hitherto, in contrast to the super-resolution for realizing high spatial resolution. This novel scheme replies on smearing out the PSF and thus poses less stringent limitations upon the object's size and position since the created dark (zero-field) area reach 8 orders of magnitude larger than the square of wavelength in size. It functions very well at arbitrarily polarized beams in three dimensions, which is also frequency-scalable in the whole electromagnetic spectrum., Comment: 11 pages, 5 figures

Published
2013

3. Superfocusing, biosensing and modulation in plasmonics

Author

Lei, Dang-Yuan and Maier, Stefan

Subjects
535
Abstract

Plasmonics could bridge the gap between photonics and electronics at the nanoscale, by allowing the realization of surface-plasmon-based circuits and plasmonic chips in the future. To build up such devices, elementary components are required, such as a passive plasmonic lens to focus free-space light to nanometre area and an active plasmonic modulator or switch to control an optical response with an external signal (optical, thermal or electrical). This thesis partially focuses on designing novel passive and active plasmonic devices, with a specific emphasis on the understanding of the physical principles lying behind these nanoscale optical phenomena. Three passive plasmonic devices, designed by conformal transformation optics, are numerically studied, including nanocrescents, kissing and overlapping nanowire dimers. Contrary to conventional metal nanoparticles with just a few resonances, these devices with structural singularities are able to harvest light over a broadband spectrum and focus it into well-defined positions, with potential applications in high efficiency solar cells and nanowire-based photodetectors and nanolasers. Moreover, thermo-optical and electrooptical modulation of plasmon resonances are realized in metallic nanostructures integrated with either a temperature-controlled phase transition material (vanadium dioxide, VO2), or ferroelectric thin films. Taking advantage of the high sensitivity of particle plasmon resonances to the change of its surrounding environment, we develop a plasmon resonance nanospectroscopy technique to study the effects of sizes and defects in the metal-insulator phase transition of VO2 at the single-particle level, and even single-domain level. Finally, we propose and examine the use of two-dimensional metallic nanohole arrays as a refractive index sensing platform for future label-free biosensors with good surface sensitivity and high-throughput detection ability. The designed plasmonic devices have great potential implications for constructing nextgeneration optical computers and chip-scale biosensors. The developed plasmon resonance nanospectroscopy has the potential to probe the interfacial or domain boundary scattering in polycrystalline and epitaxial thin films.

Published
2011
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26. Illusion Thermotics

Author

Hu, Run, primary, Zhou, Shuling, additional, Li, Ying, additional, Lei, Dang-Yuan, additional, Luo, Xiaobing, additional, and Qiu, Cheng-Wei, additional

Published
2018
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29. Electron energy-loss spectroscopy of spatial nonlocality and quantum tunneling effects in the bright and dark plasmon modes of gold nanosphere dimers

Author

Zhang, Qiang, Cai, Xiangbin, Yu, Xiang, Carregal-Romero, Susana, Parak, Wolfgang J, Sachan Ritesh, Cai, Yuan, Wang, Ning, Zhu, Ye, Lei Dang Yuan, Zhang, Qiang, Cai, Xiangbin, Yu, Xiang, Carregal-Romero, Susana, Parak, Wolfgang J, Sachan Ritesh, Cai, Yuan, Wang, Ning, Zhu, Ye, and Lei Dang Yuan

Abstract

Herein, a theoretical and experimental electron energy-loss spectroscopy (EELS) study on gold nanosphere dimers is presented, with interparticle distance d of the dimers varying from 10 nm to a few angstroms. Injecting an electron beam at the edge or the gap of the dimers excites their longitudinal bonding dipolar mode (BDM) or antibonding dipolar mode (ADM), respectively. Together with comprehensive EELS calculations within the frameworks of a classical local model, a hydrodynamic nonlocal model, and a quantum-corrected model (QCM), it is revealed that spatial nonlocality and electron tunneling have distinctively different effects on the plasmonic properties of BDM and ADM, such as resonant energy and intensity variation. Specifically, the spatial nonlocality effect blue-shifts the BDM energy and decreases its EELS intensity at d < 3 nm compared to the classical local results, while the electron tunneling effect induces a much weaker charge transfer mode (CTM) at d < 0.3 nm. However, both effects have little impact on the ADM energy though they indeed affect its EELS intensity in dramatically different manners. The experimental EELS spectra measured at varied gap size are qualitatively consistent with the numerical calculations. These results may contribute to further understanding of quantum mechanical effects in different kinds of hybridized plasmon modes in strongly coupled metallic nanostructures.

Published
2018

41. Plasmonic Enhancement and Polarization Dependence of Nonlinear Upconversion Emissions from Single Gold Nanorod@SiO2@CaF2:Yb3+,Er3+ Hybrid Core-Shell-Satellite Nanostructures

Author

He, Jijun, Zheng, Wei, Ligmajer, Filip, Chan, Chi-Fai, Bao, Zhiyong, Wong, Ka-Leung, Chen, Xueyuan, Hao, Jianhua, Dai, Jiyan, Yu, Siu-Fung, Lei, Dang Yuan, He, Jijun, Zheng, Wei, Ligmajer, Filip, Chan, Chi-Fai, Bao, Zhiyong, Wong, Ka-Leung, Chen, Xueyuan, Hao, Jianhua, Dai, Jiyan, Yu, Siu-Fung, and Lei, Dang Yuan

Abstract

Lanthanide-doped upconversion nanocrystals (UCNCs) have recently become an attractive nonlinear fluorescence material for use in bioimaging because of their tunable spectral characteristics and exceptional photostability. Plasmonic materials are often introduced into the vicinity of UCNCs to increase their emission intensity by means of enlarging the absorption cross-section and accelerating the radiative decay rate. Moreover, plasmonic nanostructures (e.g., gold nanorods, GNRs) can also influence the polarization state of the UC fluorescence - an effect that is of fundamental importance for fluorescence polarization-based imaging methods that has not been discussed previously. To study this effect, we synthesized GNR@SiO2@CaF2:Yb3+,Er3+ hybrid core-shell-satellite nanostructures with precise control over the thickness of the SiO2 shell. We evaluated the shell thickness-dependent plasmonic enhancement of the emission intensity in ensemble and studied the plasmonic modulation of the emission polarization at the single-particle level. The hybrid plasmonic UC nanostructures with an optimal shell thickness exhibit an improved bioimaging performance compared with bare UCNCs, and we observed a polarized nature of the light at both UC emission bands, which stems from the relationship between the excitation polarization and GNR orientation. We used electrodynamic simulations combined with Förster resonance energy transfer theory to fully explain the observed effect. Our results provide extensive insights into how the coherent interaction between the emission dipoles of UCNCs and the plasmonic dipoles of the GNR determines the emission polarization state in various situations and thus open the way to the accurate control of the UC emission anisotropy for a wide range of bioimaging and biosensing applications., Článek pojednává o hybridních nanostrukturách typu jádro-obálka-satelit, tvořených zlatými nanotyčkami, obálkou z oxidu křemičitého a lanthanoidy-dopovanými vzestupně-konverzními nanokrystaly. Zabývá se efektem plazmonického zesíléní a vlivem exitační polarizace a orientace nanotyček na intenzitu a polarizaci vzestupně-konverzní emise.

Published
2017

46. Ultrabroadband Optical Superchirality in a 3D Stacked-Patch Plasmonic Metamaterial Designed by Two-Step Glancing Angle Deposition

Author

Hou, Yidong, Leung, Ho Ming Dick, Chan, Che Ting, Du, Jinglei, Chan, Helen Lai Wai, Lei, Dang Yuan, Hou, Yidong, Leung, Ho Ming Dick, Chan, Che Ting, Du, Jinglei, Chan, Helen Lai Wai, and Lei, Dang Yuan

Abstract

KGaA, Weinheim Low-cost and large-scale fabrication of 3D chiral metamaterials is highly desired for potential applications such as nanophotonics devices and chiral biosensors. One of the promising fabrication methods is to use glancing angle deposition (GLAD) of metal on self-assembled dielectric microsphere array. However, structural handedness varies locally due to long-range disorder of the array and therefore large-scale realization of the same handedness is impossible. Here, using symmetry considerations a two-step GLAD process is proposed to eliminate this longstanding problem. In the proposed scheme, the unavoidable long-range disorder gives rise to microscale domains of the same handedness but of slightly different structural geometries and ultimately contributes to a broad-band response. Experimentally, a record-breaking superchiral response of circular dichroism signal of ≈11° is demonstrated and an average polarization rotation angle of 27° in the visible region on ≈1 cm2 sample is observed. Computer-aided geometric reconstruction with experimental parameters unambiguously reveal the presence of strong structural anisotropy and chirality in the prepared stacked-patch plasmonic chiral metamaterial; microscopic spectral analyses combined with full-wave electromagnetic simulations coherently provide deeper insights into the measured circular dichroism and optical activity. The observed chiroptical response can also be flexibly controlled by adjusting the deposition parameters for various potential applications.© 2016 WILEY-VCH Verlag GmbH & Co.

Published
2016

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