1. BY
CHARU LAKSHMI T R
ROLL NO. : 4
SEM 1
M.Sc MATERIALS
science
date :04/09/2013
METAMATERIALS
2. OUTLINE
INTRODUCTION
: Thoughts on invisibility
METAMATERIALS
: At a glance
HISTORY
HOW IT IS MADE ?
CURRENT STATUS
: Benefits
REFERENCES
3. METAMATERIALS
Originates from a Greek word
META means “beyond ” .
Metamaterials are woven out of materials
smaller than the wavelengths of that of light. If
you think of a Metamaterial as a piece of cloth,
the "threads" that make it up are somewhere
between 400 to 700 nanometers in size.
7. WHAT HAPPENS IF THIS IS
THE CASE ??
IT’S
INVISIBILITY
Cloaking technique
8. hypothetical invisibility !!
Conceptual approach to
change the way light
travels !!
Its not practical as light
can be bent by only those
objects which have large
mass or high energy.
Only those objects can
wrap light.
This is according to
Einstein and his general
relativity
9. How to bend light like that !!!
Refraction at surface obeys Snell’s law : n =sinθ1 / sinθ2
where ‘n’ is the refractive index of the material.
In a Mirage , a refractive index varies continuously on the road
surface.
This is what
happens in cloaking
technique !!!
11. NEGATIVE INDEX OF REFRACTION
- negative refraction can be achieved when both µr and
εr are negative.
- negative µr and εr occur in nature, but not
simultaneously.
-silver, gold, and aluminum display negative εr at
shorter
rrn
1))(())(( 2/2/2/1
jjjjj
rr eeeee
12. Negative refractive index will lead to negative
refraction , negative Doppler effect, planar focusing
etc .
Snell’s law is still satisfied when one of the materials
has a negative refractive index, but the direction of the
light ray is ‘mirror-imaged’ about the normal to the
surface.
15. Metamaterials : at a glance
Metamaterials are built of artificial or ‘meta’ atoms, which
are resonant structures such as split-ring resonators,
paired metal nanorods or nanostrips.
The ‘meta’ atoms can be engineered and arranged such
that their permittivity, permeability and refractive index
are positive , negative or even zero for a selected
frequency.
These are artificially designed subwavelength
Composites possessing extraordinary optical properties
that do not exist in nature. They can alter the propogation
of electromagnetic waves resulting in negative refraction,
subwavelength imaging and cloaking
16. The size of these features has to be much smaller than the
wavelength of light
Model Image of a nano-
fabricated material
17. They can be designed to have a refractive
index that varies throughout, even taking on
a negative value in some cases.
By carefully selecting and arranging the
components, a metamaterial antenna could
be made much smaller than a conventional
antenna — but offer similar performance.
Other exciting applications of metamaterials
include making of super lens and nanocircuits.
They also find application in stimulating the
cosmological theories such as the “Big Bang
Theory”
18. history
The possibility of negative refractive index was first raised by the
Russian physicist, Victor Veselago, in the 1960s .
He realised that if two quantities,
the electric permittivity and
the magnetic permeability, of the
material, were both negative,
Maxwell's equations of
electromagnetism would give a
negative refractive index.
19. Sir John Pendry showed practical method of making
Metamaterials in 1999 .
The recent boom in negative index materials was
inspired by him.
He made critical contributions to the field , including
prediction of
NIM-based superlens with resolution beyond the
20. This is a new tool devised by Sir John Pendry in
2006
It is called Transformation Optics
It tells us how we must shape the refractive index ,
so light goes the way we want it to go in cloaking
technique.
It makes uses of coordinate transforms and
21. METHODS USED TO MAKE
METAMATERIALS
The scientists of California university laid down copper
resonators with negative permeability, and copper wire
strips with negative permittivity, on opposite sides of the
same piece of printed circuit board. The result had
negative refractive index.
In 2006,a metamaterial made at Durham, North
Carolina and Imperial College made an object invisible
to microwave radiation
Fiberglass rings patterned
with copper elements
1 mm
22. METASCREEN is constructive strips of copper tape 66 µm
thick (thickness of human hair) attached to 100 µm thick
polycarbonate film (a material commonly used in DVD's and CD’s) in a
fishnet design .
In the test case the cylinder was 18cm long .
it only works best in the microwave regime , so the size of the object to
be cloaked has to be in “microns” .
March 2013
23. BENEFITS : RADAR PROOF STEALTH
EQUIPMENTS
A team of scientists in the USA from Purdue
University, Indiana and Norfolk State University,
Virginia have invented a new Metamaterial which
makes objects invisible to radar.
This material is composed of an array of extremely
thin silver wires (35nm in diameter) embedded in 0.4
inch squares of aluminium oxide.
24. references
EXOTIC METAMATERIALS : A REVIEW
-BY MADHURYA P. TENDULKAR .
NANO VISION ,VOL.1 ISSUE 3, OCT 2011
NANOTECH INSIGHTS
VOLUME 1, ISSUE 3, OCT 2012
PHYSICS FOR ENTERTAINMENT BOOK 2
-BY YA.PERELMAN
MIR PUBLISHERS , MOSCOW
MATERIALS TODAY
-MARCH 2009 ,VOL 12, ISSUE 3
YOUTUBE VIDEO LECTURES OF J.B.PENDRY
