排序方式: 共有26条查询结果,搜索用时 78 毫秒
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Chia‐Wei Chu Xiaomin Zhai Chih Jie Lee Po‐Hao Wang Yubo Duan Din Ping Tsai Baile Zhang Yuan Luo 《Laser \u0026amp; Photonics Reviews》2015,9(4):399-404
Transformation optics, a recent geometrical design strategy of light manipulation with both ray trajectories and optical phase controlled simultaneously, promises an invisibility cloaking device that can render a macroscopic object invisible even to a scientific instrument measuring optical phase. Recent “carpet” cloaks have extended their cloaking capability to broadband frequency ranges and macroscopic scales, but they only demonstrated the recovery of ray trajectories after passing through the cloaks, while whether the optical phase would reveal their existence still remains unverified. In this paper, a phase‐preserved macroscopic visible‐light carpet cloak is demonstrated in a geometrical construction beyond two dimensions. As an extension of previous two‐dimensional (2D) macroscopic carpet cloaks, this almost‐three‐dimensional carpet cloak exhibits three‐dimensional (3D) invisibility for illumination near its center (i.e. with a limited field of view), and its ideal wide‐angle invisibility performance is preserved in multiple 2D planes intersecting in the 3D space. Optical path length is measured with a broadband pulsed‐laser interferometer, which provides unique experimental evidence on the geometrical nature of transformation optics.
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We cloak a region from a known incident wave by surrounding the region with three or more devices that cancel out the field in the cloaked region without significantly radiating waves. Since very little waves reach scatterers within the cloaked region, the scattered field is small and the scatterers are for all practical purposes undetectable. The devices are multipolar point sources that can be determined from Green's formula and an addition theorem for Hankel functions. The cloaking devices are exterior to the cloaked region. 相似文献
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Daniel Torrent José Sánchez-Dehesa 《Wave Motion》2011,48(6):497-504
We present an analysis of acoustic cloaks based on the homogenization of two fluidlike materials, with an emphasis on periodically layered imperfect cloaks, by removing the singularities of the acoustic parameters required for ideal cloaks. The conditions that material layers should satisfy are systematically analyzed and critically discussed according to their feasibility. 相似文献
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Martin McCall 《Contemporary Physics》2013,54(6):273-286
Invisibility, a long sought-for speculation in science fiction, has been turned into reality in the laboratory through the use of a theoretical technique called Transformation Optics. The principles of transformation optics show that any desired smooth deformation of the electromagnetic field can be implemented exactly by an appropriately engineered metamaterial. All demonstrations of cloaking to date have had limitations, however, reflecting our technological inability to implement the transformation optics algorithm exactly. However, the scientific principles leading to perfect invisibility are now established, and practical improvements on the initial designs are now occurring very rapidly. Most recently, researchers have re-examined transformation optics to include time as well as space, describing and then implementing the concept of a cloak that hides events, a conceptual breakout that promises many new applications. This review describes the general ideas underlying transformation optics, and how the various types of cloak based on these ideas have been implemented practically to date. 相似文献
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隐身材料 总被引:1,自引:0,他引:1
由于超构材料(metamaterials)的发现,隐身(cloaking)科学近年来取得了长足的发展.与军事上的隐形(stealth)所不同的是,隐身指的是将电磁波的散射在各个方向上都完全消除,从而实现神话故事或科幻小说中那种真正的全方位、全角度的"消失".隐身也因其重要的科学价值以及将对人类生活产生跨越式的改变而成为国际上的科研热点.除了隐身之外,科学家还证明了可以将物体变成任意的幻像,从而在光学上实现了孙悟空的"七十二变",这被称为幻像光学(illusion optics).未来,隐身和幻像光学的发展有望将人类的极限想象变为现实.文章介绍了作者在隐身和幻像领域里的一些工作. 相似文献
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Spacetime or ‘event’ cloaking was recently introduced as a concept, and the theoretical design for such a cloak was presented for illumination by electromagnetic waves [McCall et al., J. Opt. 2011]. Here it is described how event cloaks can be designed for simple wave systems, using either an approximate ‘speed cloak’ method, or an exact full‐wave one. Further, details of many of the implications of spacetime transformation devices are discussed, including their (usually) directional nature, spacetime distortions (as opposed to cloaks), and how leaky cloaks manifest themselves. More exotic concepts are also addressed, in particular concepts that follow naturally on from considerations of simple spacetime transformation devices, such as spacetime modeling and causality editors. A proposal for implementing an interrupt‐without‐interrupt concept is described. Finally, the design for a time‐dependent ‘bubbleverse’ is presented, based on temporally modulated Maxwell's Fisheye transformation device (T‐device) in a flat background spacetime. 相似文献
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随着理论研究的深入和现代微加工技术的进步,对支持表面等离激元的金属微纳结构体系的研究已形成了一门新兴学科方向,即表面等离激元光子学。由于表面等离激元具有独特的光学特性,在数据存储、超分辨成像、光准直、太阳能电池、生物传感器以及负折射材料等方面有着重要的应用前景,成为当前广受国内外学者重视的热点研究领域之一。本文对表面等离激元的特点、基本现象,以及其带来的新颖效应及其应用研究前景的最新发展进行了介绍。 相似文献
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