Department of Physics, Korea University , Seoul 136-701, Korea.
Sci Rep. 2013;3:1062. doi: 10.1038/srep01062. Epub 2013 Jan 14.
Reducing unwanted reflections through impedance matching, called anti-reflection, has long been an important challenge in optics and electrical engineering. Beyond trial and error optimization, however, a systematic way to realize anti-reflection is still absent. Here, we report the discovery of an analytic solution to this long standing problem. For electromagnetic waves, we find the graded permittivity and permeability that completely remove any given impedance mismatch. We demonstrate that perfect broadband anti-reflection is possible when a dispersive, graded refractive index medium is used for the impedance-matching layer. We also present a design rule for the ultra-thin anti-reflection coating which we confirm experimentally by showing the anti-reflection behavior of an exemplary λ/25-thick coating made of metamaterials. This work opens a new path to anti-reflection applications in optoelectronic device, transmission line and stealth technologies.
通过阻抗匹配来减少不需要的反射，即抗反射，一直以来都是光学和电气工程领域的一个重要挑战。然而，除了反复试验和优化之外，仍然缺乏一种系统的方法来实现抗反射。在这里，我们报告了这一长期存在的问题的解析解的发现。对于电磁波，我们找到了完全消除任何给定阻抗失配的渐变介电常数和磁导率。我们证明，当使用色散渐变折射率介质作为阻抗匹配层时，完美的宽带抗反射是可能的。我们还提出了一种超薄膜抗反射涂层的设计规则，并通过展示由超材料制成的典型 λ/25 厚涂层的抗反射行为来实验验证。这项工作为在光电设备、传输线和隐身技术中的抗反射应用开辟了一条新途径。
