张婧婧、皇甫江涛、罗宇、陈红胜（通讯作者）、孔金瓯、Bae-Ian Wu发表在Physical Review B上的关于多层环境背景下隐身衣设计的论文《Cloak for multilayered and gradually changing media》于2008年2月20日被《自然中国》选为来自中国大陆和香港的突出科学研究成果，论文的研究亮点刊登在《自然中国》网页。

在实际军事应用中，比如军舰、航母都是在水上行进，要使军舰同时实现对水上及水下探测器完美隐身需要有合理的设计策略。本文通过研究柱体异向介质在多层及渐变介质中实现对电磁波隐身的情况，推广提出了在任意非均匀各向同性介质中设计隐身衣的设计思路，这在实际应用中具有重要的理论指导意义。

相关链接及内容：

http://www.nature.com/nchina/archive/physics/subject_nchina_s11_2008.html

《Nature China: Research Highlight》

Metamaterials: Hiding from a different world

Original article citation

Zhang, J. et al. Cloak for multilayered and gradually changing media. Phys. Rev. B 77, 035116 (2008).

Invisibility cloaks could be designed to conceal objects even when the background medium is of varying composition

Recent theoretical and experimental work has brought the idea of invisibility cloaks closer to reality. However, most approaches would only work when the surrounding medium is all of the same composition, or homogeneous. Hongsheng Chen and co-workers at Zhejiang University in Hangzhou and Massachusetts Institute of Technology¹ have described for the first time how to make cloaks that could work in inhomogeneous media.

The 'cloaking' concept uses a cylindrical or spherical shell to bend light around the object to be concealed. The shell is made of metamaterial (a man-made material whose optical properties result from its structure) that has a negative refractive index so that it bends light in the opposite direction to conventional materials. However, the amount of bending depends on the light-bending properties of the medium surrounding the cloak.

Chen and co-workers showed that it is possible to construct a cloak that works in a background comprising two different homogeneous media. This could be useful for concealing a ship at sea, where the surrounding medium includes air and water.

The researchers also found a way to tailor the physical properties of a cloak so that it works in a medium that gradually changes over space (pictured). This sort of cloaking could conceal objects in a hot desert where the density of air is different at different heights.

The authors of this work are from:
The Electromagnetics Academy at Zhejiang University, Zhejiang University, Hangzhou, China; Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.