paper presentation on metamaterials

1. META MATERIALS

2. ABSTRACT
Meta materials are artificial materials
engineered to have properties that may not
be found in nature. They are assemblies of
multiple individual elements fashioned from
conventional microscopic materials such as
metals or plastics, but the materials are
usually arranged in periodic patterns. Meta
materials gain their properties not from their
composition, but from their exactingly-
designed structures. Their precise shape,
geometry, size, orientation and arrangement
can affect the waves of light or sound in an
unconventional manner, creating material
properties which are unachievable with
conventional materials. These meta materials
achieve desired effects by incorporating
structural elements of sub-wavelength sizes,
i.e. features that are actually smaller than the
wavelength of the waves they affect
The primary research in meta materials
investigates materials with
negative refractive index Negative refractive
index materials appear to permit the creation
of super lenses which can have a spatial
resolution below that of the wavelength. In
other work, a form of 'invisibility' has been
demonstrated at least over a narrow wave
band with gradient-index materials.
Although the first meta materials were
electromagnetic acoustic and seismic meta
materials are also areas of active research.
Potential applications of meta materials are
diverse and include
remote aerospace applications,
sensor detection and infrastructure
monitoring, smart solar
power management, public
safety, radomes, high-frequency battlefield
communication and lenses for high-gain
antennas, improving ultrasonic sensors, and
even shielding structures from earthquakes.
The research in meta materials is
interdisciplinary and involves such fields
as electrical engineering,
electromagnetics, solid state physics,
microwave and antennae
engineering, optoelectronics, classic optics,
material sciences, semiconductor
engineering, Nano science and others
1. INTRODUCTION
The things which our eyes are not able to see
are considered as “Invisible”. Light is
neither absorbed nor reflected by the objects,
passing like water flowing around a rock. As
a result, only the light from behind the
objects can be seen. The devices which are
going to make us hide are invisibility
devices. Researchers at the University of
California at Berkeley, whose work is
funded by the American military, have
engineered materials that can control
light’s direction of travel. The world’s two
leading scientific journals, Science and
Nature, are expected to report the results in
near future. . The concept of invisibility
would involve surrounding the object by a

3. "meta material”. Meta-material is a type of
composite material that has unusual
electromagnetic properties. According to the
researchers, light rays incident on the
material would be bent around the object,
only to emerge on the other side in exactly
the same direction as they began. Although
the work is only theoretical, the researchers
reckon that materials invisible to radio
waves could be produced within five years.
2. META-MATERIAL
The new "meta-materials," whose physical
structure bends visible light in a way that
ordinary materials don't, may help efforts to
make an invisibility cloak that could guide
light around an object so that neither a
reflection nor a shadow would be created.
Researchers have developed meta-materials
that show these unusual light-bending
abilities for other parts of the
electromagnetic spectrum, notably for
microwaves, but efforts to do this with
visible light have been limited to flat, two-
dimensional systems because the shorter the
wavelength, as in visible light, the smaller
the features of the man made metamaterial.
Figure 1. Bending of light in meta-
material
There are some scientific catches that the
tale-tellers never had to worry about:
• For a total invisibility effect, the
waves passing closest to the cloaked
object would have to be bent in such
a way that they would appear to
exceed relativity's light speed limit.
Fortunately, there's a loophole in
Albert Einstein's rules of the road
that allows smooth pulses of light to
undergo just such a phase shift.
• The invisibility effect would work
only for a specific range of
wavelengths. "There is a price to be
paid if you want a thin cloak, in that

4. it operates only over a narrow range
of frequencies," Pendry said.
• The cloak could be made to cover a
volume of any shape, but "you can't
flap your cloak," Pendry said.
Moving the material around would
spoil the effect.
• The tiny structures embedded in the
metamaterial would have to be
smaller than the wavelength of the
electromagnetic rays you wanted to
bend. That's a tall order for optical
invisibility, because the structures
would have to be on the scale of
nanometers, or billionths of a meter.
It's far easier to create radar
invisibility, Pendry said: "You're
talking millimeters" — that is,
thousandths of a meter.
3. RESEARCH WORKS IN FIELD
OF INVISIBILITY
3.1 Xiang Zhang
Xiang Zhang the leader of the
researchers, said: “In the case of
invisibility cloaks or shields, the material
would need to curve light waves
completely around the object like a river
flowing around a rock.”
Figure 2. Meta-material
An observer looking at the cloaked
object would then see light from behind
it – making it seem to disappear.
Substances capable of achieving such
feats are known as “meta-materials” and
have the power to “grab”
electromagnetic radiation and deflect it
smoothly. No such material occurs
naturally and it is only in the past few
years that Nano-scale engineering,
manipulating matter at the level of atoms
and molecules, has advanced sufficiently
to give scientists the chance to create
them. The tiny scale at which such
researchers must operate is astonishing
in itself. Zhang’s researchers had to
construct a material whose elements
were engineered to within about
0.00000066 of a meter. The military
funding that Zhang has won for his
research shows what kind of applications
it might be used for, ushering in a new
age of stealth technology.

5. 3.2 Researchers at the University of
California
Researchers at the University of
California at Berkeley, whose work is
funded by the American military, have
engineered materials that can control
light’s direction of travel. The world’s
two leading scientific journals, Science
and Nature, are expected to report the
results in near future.
3.3 Imperial College London
It follows earlier work at Imperial
College London that achieved similar
results with microwaves. Like light,
these are a form of electromagnetic
radiation but their longer wave-length
makes them far easier to manipulate.
Achieving the same effect with visible
light is a big advance.
4. Cloak and shadow
This is a huge step forward, a
tremendous achievement. It's a careful
choice of the right materials and the right
structuring to get this effect for the first
time at these wavelengths. There could
be more immediate applications for the
devices in telecommunications. What's
more, they could be used to make better
microscopes, allowing images of far
smaller objects than conventional
microscopes can see. And a genuine
cloaking effect isn't far around the
corner. "In order to have the 'Harry
Potter' effect, you just need to find the
right materials for the visible
wavelengths," says Prof Hess, "and it's
absolutely thrilling to see we're on the
right track."
5. APPLICATIONS AND FUTURE
PROSPECTS:
• There'd be plenty of applications
in the civilian world as well, even
for rudimentary cloaking devices.
For example, you could create
receptacles to shield sensitive
medical devices from disruption
by MRI scanners, or build cloaks
to route cellphone signals around
obstacles.
• Pendry's team proposed
constructing all-over cloaking
devices, the other research paper
describes a simpler method that
would involve shaping the meta-
materials into cylindrical
cloaking devices. The method
could also work to block sound
waves — like the cone of silence
on the "Get Smart" TV show, but
not as impractical.
6. Barrier in development of
Invisibility devices:

6. • Although we have thorough
knowledge of theoretical concept
of invisibility but we have not
enough practical implementation
of these concepts.
• Meta-material still needs more
consideration and a lot has
remained undiscovered and
needs thorough study.
• Security concern is another
serious issue.
8. REFERENCES
• Electronics for You, April,
2007Business week, August 5,
1996.
• The New York times magazine,
June, 2000.
• Researchers from Duke
University, USA
• Researchers from imperial
College London Findings of
Xiang Zhang
• Researchers at the University of
California Imperial College
London
• www.Physicsworld.com
• www.Sciencedaily.com
• Science Reporter,april,2005

7. • Although we have thorough
knowledge of theoretical concept
of invisibility but we have not
enough practical implementation
of these concepts.
• Meta-material still needs more
consideration and a lot has
remained undiscovered and
needs thorough study.
• Security concern is another
serious issue.
8. REFERENCES
• Electronics for You, April,
2007Business week, August 5,
1996.
• The New York times magazine,
June, 2000.
• Researchers from Duke
University, USA
• Researchers from imperial
College London Findings of
Xiang Zhang
• Researchers at the University of
California Imperial College
London
• www.Physicsworld.com
• www.Sciencedaily.com
• Science Reporter,april,2005