The science of invisibility

1. METAMATERIALS
SOUMEN GIRI
ROLL NO.- 16MS6019
Materials Science centre
IIT KHARAGPUR

2. What is a metamaterial?
 Metamaterials are made from
assemblies of multiple
individual elements fashioned
from conventional microscopic
materials such as metals or
plastics, but the materials are
usually arranged in periodic
patterns.

3. METAMATERIAL BACKGROUND
 Do not depend upon chemical composition
 Depend on the geometry of the structure
units.
 Metamaterials are artificial engineered
composite structures.
 Not commonly found in nature.

4. BACKGROUND
𝜀,
  0  0
  0


 0
 0
 0
  0  0


6. Refractive Index
 The refractive index, n, of a medium is defined as the
ratio of the speed, C, of a wave phenomenon such as
light or sound in a reference medium to the phase
Velocity Vp, of the wave in the medium.
 n = C / Vp
= r  r

7. NEGATIVE REFRACTIVE INDEX
How to achieve negative refractive index?
n  r  r
Negative refractive index can be achieved when (r and r ) are
negative
=
= -1

8. DNG
medium
DPS
medium
E E
S S
HH
Left handed medium and
right handed medium

9. Negative refractive index
a) Calculated ray-tracing image of a metal rod in an empty drinking glass.
b) Same scenery, but the glass is filled with normal water, n 1.3 , leading to
ordinary refraction.
c) The water is replaced by “water” with a fictitious refractive index of n  1.3

10. E
k
H
Double Negative
Material
Left handed
Material
S
Other names
Negative refractive index
material

11. MANUFACTURING
Upto today metamaterials have mostly been
manufractured by the technology electron beam
lithography.
Thease technique have the disadvantage of being
quite expansive and slow and obtaining large areas.
Material science and technologies currently under
investigation to fabricate metamaterials are self
assembly.

12.  At microwave frequencies, the first real invisibility cloak
was realized in 2006. However, only a very small object
was imperfectly hidden.
 In 2007, one researcher stated that for metamaterial
applications to be realized, several goals must be
achieved.
GOAL OF DEVELOPMENT

13. Application of Metamaterials
 Metamaterial antenna
 Cloaking device
 Superlens
 Invisible Submarines
 Photonics OR opto-electronics
 Create the oft-discussed, Invisible Man
 Perfect Absorber of light
 Ultra high capacity storage devices etc.

14. Metamaterial antenna
• Metamaterial antennas are a class of
antennas which use metamaterials to
increase performance of miniaturized
(electrically small) antenna systems.
• Metamaterial antennas radiate as
much as 95 percent of an input radio
signal.
• Experimentally metamaterial antennas
are as small as one-fiftieth of a
wavelength and could have further
decrease in size.
• Some applications for metamaterial
antennas are wireless
communications, space
communication, satellites etc.

15. Metamaterial cloaking
Metamaterial cloaking is the usage of materials in an invisibility
cloak. Metamaterials direct and control the propagation and
transmission of specified paths of the light spectrum and
demonstrate the potential to render an object seemingly
invisible.

16. Superlens
• A practical superlens is a lens which uses metamaterials to go
beyond the diffraction limit. The diffraction limit is a feature
of convectional lenses and microscopes that limits the
fineness of their resolution. Many lens designs have been
proposed that go beyond the diffraction limit in some way but
there are constraints and obstacles involved in realizing each
of them.

17. Future Work
• Optimize process
• Create more complicated 3D structures
• Characterize 3D structure properties
• Explore new thickness and exposure times

18. REFERENCES
• https://en.wikipedia.org/wiki/Metamaterial
• Nanostructured Metamaterials, By Anne F.de Baas