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An optical cloak made of dielectrics


Invisibility devices have captured the human imagination for many years. Recent theories have proposed schemes for cloaking devices using transformation optics and conformal mapping1,2,3,4. Metamaterials5,6, with spatially tailored properties, have provided the necessary medium by enabling precise control over the flow of electromagnetic waves. Using metamaterials, the first microwave cloaking has been achieved7 but the realization of cloaking at optical frequencies, a key step towards achieving actual invisibility, has remained elusive. Here, we report the first experimental demonstration of optical cloaking. The optical ‘carpet’ cloak is designed using quasi-conformal mapping to conceal an object that is placed under a curved reflecting surface by imitating the reflection of a flat surface. The cloak consists only of isotropic dielectric materials, which enables broadband and low-loss invisibility at a wavelength range of 1,400–1,800 nm.

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Figure 1: The carpet cloak design that transforms a mirror with a bump into a virtually flat mirror.
Figure 2: Scanning electron microscope image of the carpet cloak layout.
Figure 3: Optical carpet cloaking at a wavelength of 1,540 nm.
Figure 4: Wavelength dependence of the carpet cloak.

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We acknowledge financial support from the US Department of Energy under Contract No. DE-AC02-05CH11231 and from the US Army Research Office (ARO) MURI program 50432-PH-MUR. T.Z. acknowledges a fellowship from the Alexander von Humboldt Foundation.

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Correspondence to Xiang Zhang.

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Valentine, J., Li, J., Zentgraf, T. et al. An optical cloak made of dielectrics. Nature Mater 8, 568–571 (2009).

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