scispace - formally typeset
Search or ask a question
Author

Yu Luo

Bio: Yu Luo is an academic researcher from Tianjin University. The author has contributed to research in topics: Metamaterial & Plasmon. The author has an hindex of 42, co-authored 222 publications receiving 5410 citations. Previous affiliations of Yu Luo include South China University of Technology & Imperial College London.


Papers
More filters
Journal ArticleDOI
TL;DR: The first realization of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals is reported, capable of hiding, for a specific light polarization, three-dimensional objects of the scale of centimetres and millimetres.
Abstract: Invisibility cloaks, which used to be confined to the realm of fiction, have now been turned into a scientific reality thanks to the enabling theoretical tools of transformation optics and conformal mapping. Inspired by those theoretical works, the experimental realization of electromagnetic invisibility cloaks has been reported at various electromagnetic frequencies. All the invisibility cloaks demonstrated thus far, however, have relied on nano- or micro-fabricated artificial composite materials with spatially varying electromagnetic properties, which limit the size of the cloaked region to a few wavelengths. Here, we report the first realization of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals. The cloak operates at visible frequencies and is capable of hiding, for a specific light polarization, three-dimensional objects of the scale of centimetres and millimetres. Our work opens avenues for future applications with macroscopic cloaking devices.

435 citations

Journal ArticleDOI
TL;DR: A local analogue model is presented and it is shown that spatial nonlocality can be represented by replacing the nonlocal metal with a composite material, comprising a thin dielectric layer on top of a local metal.
Abstract: Surface plasmons on metals can concentrate light into subnanometric volumes and on these near atomic length scales the electronic response at the metal interface is smeared out over a Thomas-Fermi screening length. This nonlocality is a barrier to a good understanding of atomic scale response to light and complicates the practical matter of computing the fields. In this Letter, we present a local analogue model and show that spatial nonlocality can be represented by replacing the nonlocal metal with a composite material, comprising a thin dielectric layer on top of a local metal. This method not only makes possible the quantitative analysis of nonlocal effects in complex plasmonic phenomena with unprecedented simplicity and physical insight, but also offers great practical advantages in their numerical treatment.

233 citations

Journal ArticleDOI
01 Mar 2020
Abstract: Metasurfaces are engineered surfaces that consist of subwavelength periodic elements and can be used to manipulate electromagnetic waves. Multifunctional or reconfigurable electromagnetic meta-devices based on a direct-current biasing system can be built using lumped electronic components. However, such meta-devices require bulky power supplies, field-programmable gate arrays, electrical wires and complex control circuits. Here, we report a digital metasurface platform that can be programmed optically to implement electromagnetic functions. Our digital platform has 6 × 6 subarrays, each of which contains 4 × 4 metasurface elements based on electronic varactors integrated with an optical interrogation network based on photodiodes. The interrogation network can convert visible light illumination patterns to voltages and applies bias to the metasurface elements, generating specific microwave reflection phase distributions. To illustrate the capabilities of our approach, we use the optically driven digital metasurface for external cloaking, illusion and dynamic vortex beam generation. A digital platform that integrates a metasurface based on electronic varactors with an optical interrogation network based on photodiodes can be programmed by visible light to implement electromagnetic functions, including microwave cloaking, illusion and vortex beam generation.

174 citations

Journal ArticleDOI
TL;DR: In this paper, a broadband dual-polarized antenna array with five elements for the band is developed for base station application, and the measured results show achievement of impedance bandwidth of 45% for both ports, port-to-port isolation $>$ 25 dB, a stable radiation pattern with 3-dB beamwidth $68^{\circ}\pm 2^{circ}$ at H-plane and V-plane.
Abstract: A broadband $\pm 45^{\circ}$ dual-polarized base station antenna is proposed for 2G/3G/LTE bands. The proposed antenna has Y-shaped feeding lines to impart a wide impedance bandwidth to it, and a rectangular box-shaped reflector to enhance its stability in radiation patterns over the operating frequencies. A prototype of the proposed antenna is designed, fabricated, and tested. The measured results show achievement of impedance bandwidth of 45% for $\hbox {SWR} at both ports, port-to-port isolation $>$ 25 dB , a stable radiation pattern with 3-dB beamwidth $68^{\circ}\pm 2^{\circ}$ at H-plane and V-plane, and a stable antenna gain of 8.2 $\pm$ 0.6 dBi from 1.7 to 2.7 GHz. A broadband dual-polarized antenna array with five elements for the band is developed for base station application. Measurements show achievement of array gain of 14.8 $\pm$ 1.4 dBi, 3-dB beamwidth $66.56^{\circ}\pm 2.22^{\circ}$ at H-plane at port 1 and $64.85^{\circ}\pm 4.96^{\circ}$ at port 2 with $\hbox {SWR} over the operating frequency band. Simulation results have a good agreement with measurement ones.

166 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated a general class of electromagnetic devices created with any continuous transformation functions by rigorously calculating the analytical expressions of the electromagnetic field in the whole space, and they proposed a spherical field rotator which functions as not only a wave vector rotator but also a polarization rotator depending on the orientations of the spherical rotator with respect to the incident wave direction.
Abstract: We investigate a general class of electromagnetic devices created with any continuous transformation functions by rigorously calculating the analytical expressions of the electromagnetic field in the whole space. Some interesting phenomena associated with these transformation devices, including the invisibility cloaks, concentrators, and field rotators, are discussed. By carefully choosing the transformation function, we can realize cloaks, which are insensitive to perturbations at both the inner and outer boundaries. Furthermore, we find that when the coating layer of the concentrator is realized with left-handed materials, energy will circulate between the coating and the core, and the energy transmitted through the core of the concentrator can be much bigger than that transmitted through the concentrator. Therefore, such concentrator is also a power flux enhancer. Finally, we propose a spherical field rotator, which functions as not only a wave vector rotator but also a polarization rotator, depending on the orientations of the spherical rotator with respect to the incident wave direction. The functionality of these transformation devices are all successfully confirmed by our analytical full-wave method, which also provides an alternate computational efficient validation method in contrast to numerical validation methods.

156 citations


Cited by
More filters
28 Jul 2005
TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1(PfPMP1)与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员,通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

18,940 citations

Journal ArticleDOI
TL;DR: An overview of the key aspects of graphene and related materials, ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries are provided.
Abstract: We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.

2,560 citations

Journal ArticleDOI
TL;DR: Digital metamaterials consisting of two kinds of unit cells whose different phase responses allow them to act as ‘0’ and ‘1’ bits are developed to enable controlled manipulation of electromagnetic waves.
Abstract: Smart materials offering great freedom in manipulating electromagnetic radiation have been developed. This exciting new concept was realized by Tie Jun Cui and co-workers at the Southeast University, China, who developed digital metamaterials consisting of two kinds of unit cells whose different phase responses allow them to act as ‘0’ and ‘1’ bits. These cells can be judiciously arranged in sequences to enable controlled manipulation of electromagnetic waves. This is one-bit coding; higher-bit coding is possible by employing more kinds of unit cells. The researchers developed a metamaterial cell whose binary response can be controlled by a biased diode. By using a field-programmable gate array, they demonstrated that this digital metamaterial can be programmed. Such metamaterials are attractive for controlling radiation beams in antennas and for realizing other ‘smart’ metamaterials.

1,767 citations

01 Jan 2016

1,715 citations