Invisible Cloak Made of
Metamaterial
B96901128 王郁翔
Outline
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1. Basic Concepts
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2. Free-Space Cloak in 2006
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3. Carpet Cloak in 2008
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4. Carpet Cloak in 2009
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5. Conclusions
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6. References
Basic Concepts

Transformation optics and quasiconformal
mapping.
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Inhomogeneous material—curved space,
apply Fermat’s principle.
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Cloaking, concentrating, rotating, bending,
black hole,..
Equivalence of two space
Free-Space Cloak in 2006
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First proposed by Pendry[1] and
Leonhardt[2].theorem in book[3-4]
Free-Space Cloak in 2006
Free-Space Cloak in 2006

Used reduced parameter to realized in
microwave frequency[5].
Free-Space Cloak in 2006
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Drawback
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1. Singular parameter
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2. Need to use resonant structure,
narrow bandwidth and high loss.

3. Anisotropic
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Hard to fabricate and applied.
Carpet Cloak in 2008
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Instead crushed cloaked object to a point,
we can also crushed to a line or a
sheet(carpet cloak).

Broad-band, low loss and isotropic, easy
to fabricate.

Hide the tank or the aircraft on the
ground.
Carpet Cloak in 2008
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Proposed by Pendry[6]
Carpet Cloak in 2008

The optimal map is generated by
minimizing the Modified-Liao functional
upon slipping BC[3].

Choose smallest anisotropy factor(1.042).
Carpet Cloak in 2008

Realized in microwave frequency[7] and
optic frequency[8-9].
Carpet Cloak in 2008
Carpet Cloak in 2008

Drawback

1.Carpet cloak has very large size (height
ratio=65.7)

2.Background is not free space.

Therefore, T.J.Cui proposed a compactsized broadband carpet cloak[10].
Carpet Cloak in 2009

Set background to free space, and use
n=1 to replace the region where n<1.

Height ratio from 65.7 to 7.33.
Carpet Cloak in 2009
Carpet Cloak in 2009

Different h, different ε.
Carpet Cloak in 2009

Measure at different frequency.
Carpet Cloak in 2009

Compare full-parameter carpet cloak and
simplified carpet cloak(simulation).
Directive Free-Space Cloak
Directive Free-Space Cloak

Simulate and measure at different
frequency.
Directive Free-Space Cloak
Conclusions

Compact-sized, broadband carpet cloak is
developed, and it represents a major step
towards real applications of invisibility
devices.
Reference
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[1] J. B. Pendry, D. Schurig, and D. R. Smith, “Controlling
electromagnetic fields,” Science 312, 1780-1782 (2006).
[2] U. Leonhardt, ”Optical conformal mapping,” Science 312, 17771780 (2006).
[3] P. Knupp, and S.Steinberg,“Fundamentals of Grid Generation,”
(CRC Press, Boca Raton, 1994).
[4] J. F. Thompson, B. K. Soni, and N. P. Weatherill, ”Handbook of
Grid Generation,” (CRC Press, Boca Raton,1999).
[5] D. Schurig, et al. ”Metamaterial electromagnetic cloak at
microwave frequencies,” Science 314, 977-980 (2006).
Reference
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[6] J. Li, and J. B. Pendry, ”Hiding under the carpet: A new strategy
for cloaking,” Phys. Rev. Lett. 101, 203901 (2008).
[7] R. Liu, C. Ji, J. J. Mock, J.Y. Chin, T. J. Cui, and D. R. Smith,
”Broadband ground-plane cloak,” Science 323, 366-369 (2009).
[8] J.Valentine, J. Li, T. Zentgraf, G. Bartal, and X. Zhang, ”An optical
cloak made of dielectrics,” Nat. Mater. 8,568-571 (2009).
[9] L. H. Gabrielli, J. Cardenas, C. B. Poitras, and M. Lipson, ”Silicon
nanostructure cloak operating at optical frequencies,” Nat. Photon.,
in press (2009).
[10] H.F. Ma, W.X. Jiang, X.M.Yang, X.Y. Zhou, and T. J. Cui“Caopactsize and Broadband Carpet Cloak and Free-space Cloak”,2009.