AAWSAP DIRD, Invisibility Cloaking Theory and Experiments, March 2010

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Figure 16. Demonstration of Negative Refraction With "Bulk" Optical Metamaterials Made of
Nanowires27
Fundamental Problem
The demonstrated microwave-cloaking device only works correctly for microwave
radiation of a specific frequency (wavelength), and the proposed optical cloaking device
would also work for just one frequency; that is, for only one color. Light of different
colors would be severely distorted. So, to see things disappear in a cloaking device, one
should wear tinted glasses of the required color, which of course completely defeats the
purpose. This design flaw is inevitable, 28 no matter how much progress is made in the
technology of metamaterials, for the following reason: the device is designed such that
light waves traveling around the object enclosed by the cloaking device are completely
indistinguishable from light waves propagating through empty space. This is achieved
by implementing the coordinate transformation shown below in Figure 17.29
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