Download Plasmonics Seminar Report

PLASMONICS
A
NEW DEVICE
TECHNOLOGY
PRESENTED BY:
C . Deepika Kameswari
R. Nikhila Reddy
[email protected]
[email protected]
ECE III/IV (II-SEM)
ECE III/IV (II-SEM)
Contact no.: 9985387080
C M R COLLEGE OF ENGG. & TECHNOLOGY
PLASMONICS – THE NEXT DEVICE TECHNOLOGY
fixed positive ions with a plasma frequency.
Abstract:
Plasmonics,
Electronic circuits provide us with the ability to
control the transport and storage of electrons.
However, the performance of electronic circuits
then,
is
the
technology
of
transmitting these lights like waves along
nanoscale wires. With every wave, we can, in
principle, carry loads of information.
is now becoming rather limited when digital
information needs to be sent from one point to
another. Photonics offers an effective solution to
this
problem
by
implementing
optical
communication systems based on optical fibers
and
photonic
circuits.
Unfortunately,
the
micrometer-scale bulky components of photonics
have limited the integration of these components
into electronic chips, which are now measured in
nanometers. Surface plasmon–based circuits,
which merge electronics and photonics at the
nanoscale, may offer a solution to this sizecompatibility problem. Here we review the
current status and future prospects of plasmonics
Thus development of chip-scale electronics and
photonics has led to remarkable data processing
and transport capabilities that permeate almost
every facet of our lives. Plasmonics is an
exciting new device technology that has recently
emerged. It exploits the unique optical properties
of metallic nanostructures to enable routing and
manipulation of light at the nanoscale. A
tremendous
integrating
synergy
can
plasmonic,
be
attained
electronic,
by
and
conventional dielectric photonic devices on the
same chip and taking advantage of the strengths
of each technology.
in various applications including plasmonic
chips, light generation, and nanolithography.
Introduction:
The term Plasmonics is derived from ‘plasmons’,
which are the quanta associated with longitudinal
waves propagating in matter through the
collective motion of large numbers of electrons.
Plasma is a medium with equal concentration of
positive and negative charges, of which at least
one charge type is mobile. In as solid, the
negative charges of the conduction electrons are
balanced by an equal concentration of positive
charge of the ion cores. A plasma oscillation in a
metal is a collective longitudinal excitation of the
conduction electron gas against a background of
The
ever-increasing
demand
for
faster
information transport and processing capabilities
is undeniable. Our data-hungry society has
driven enormous progress in the Si electronics
industry and we have witnessed a continuous
progression towards smaller, faster, and more
efficient electronic devices over the last five
realize
decades. The scaling of these devices has also
processing speeds. The metals commonly used in
brought about a myriad of challenges. Currently,
electrical interconnection such as Cu and Al
two of the most daunting problems preventing
allow the
significant increases in processor speed are
polaritons (SPPs). SPPs are electromagnetic
thermal and signal delay issues associated with
waves that propagate along a metal-dielectric
electronic interconnection. Optical interconnects,
interface and are coupled to the free electrons in
on
the metal.
the
other
hand,
possess
an
almost
the
dream
of
excitation of
significantly
surface
faster
plasmon-
unimaginably large data carrying capacity, and
may
offer
interesting
for
From an engineering standpoint, an SPP can be
Optical
viewed as a special type of light wave. The
alternatives may be particularly attractive for
metallic interconnects that support such waves
future chips with more distributed architectures
thus serve as tiny optical waveguides termed
in which a multitude of fast electronic computing
plasmonic waveguides. The notion that the
units (cores) need to be connected by high-speed
optical mode (‘light beam’) diameter normal to
links. Unfortunately, their implementation is
the metal interface can be significantly smaller
hampered by the large size mismatch between
than the wavelength of light has generated
electronic and dielectric photonic components.
significant excitement and sparked the dream
Dielectric photonic devices are limited in size by
that one day we will be able to interface
the fundamental laws of diffraction to about half
nanoscale electronics with similarly sized optical
a wavelength of light and tend to be at least one
(plasmonic) devices. It is important to realize
or two orders of magnitude larger than their
that, with the latest advances in electromagnetic
nanoscale electronic counterparts. This obvious
simulations and current complementary metal-
size mismatch between electronic and photonic
oxide
components presents a major challenge for
fabrication techniques, a variety of functional
interfacing these technologies. Further progress
plasmonic structures can be designed and
will require the development of a radically new
fabricated in a Si foundry right now. Current Si-
chip-scale device technology that can facilitate
based integrated circuit technology already uses
information transport between nanoscale devices
nanoscale metallic structures, such as Cu and Al
at optical frequencies and bridge the gap between
inter-connects,
the
between transistors on a chip. This mature
circumventing
world
these
of
new
solutions
problems.
nanoscale
electronics
and
microscale photonics.
semiconductor
to
route
(CMOS)-compatible
electronic
signals
processing technology can thus be used to our
advantage in integrating plasmonic devices with
Plasmonics as a new device technology
their
electronic
counterparts.
In
and
some
dielectric
cases,
photonic
plasmonic
Metal nanostructures may possess exactly the
waveguides may even perform a dual function
right combination of electronic and optical
and simultaneously carry both optical and
properties to tackle the issues outlined above and
electrical signals, giving rise to exciting new
nano-structured materials must be used to
capabilities.
fabricate effective plasmonic devices. For this
reason, plasmonics is frequently associated with
nanotechnology.
Plasmonics describes how ultra-small metallic
structures
of
various
shapes
capture
and
manipulate light and provides practical design
tool for nanoscale optical components. The fact
that
light
interacts
with
nanostructures
overcomes the belief held for more than a
century that light waves couldn’t interact with
anything smaller than their own wavelengths.
Fig (a) the red arrow shows how an SPP is
launched from an excitation spot onto a metal
film surface.
When light of a specific frequency strikes a
plasmon
that
oscillates
at
a
compatible
frequency, the energy from light is harvested by
the plasmon, converted into electrical energy that
Plethora of Benefits:
propagates
Plasmon
waves
through
the
nanostructure
and
eventually converted back into light.
are of particular
interest
these
because
are
at
Limitations do exist!
The
optical
plasmonics
frequencies. The
higher
now
the
the
frequency
of
today’s
electronic
microprocessors.
right
mainly
that plasmons can
wave, the more
frequencies are about 100,000 times greater than
is
of
limited by the fact
frequency of the
the information we can transport. Optical
potential
typically travel only several millimeters before
they peter out. Chips, meanwhile, are typically
about a centimeter across, so plasmons can’t yet
go the whole distance. The distance that a
plasmon can travel before dying out is a function
The key is using a material with a low refractive
index, ideally negative, such that the incoming
electromagnetic energy is reflected parallel to the
surface of the material and transmitter along its
length as far as possible. There exists no natural
material with a negative refractive index, so
of several aspects of the metal. But for optimal
transfer through a wire of any metal, the surface
of contact with surrounding materials must be as
smooth as possible and the metal should not have
any impurities.
For most wavelengths of visible light, aluminum
Plasmonics has also been used in biosensors.
allows plasmons to travel farther than other
When a particular protein or DNA molecule rests
metals such as gold, silver and copper. It is
on the surface of a plasmon-carrying metallic
somewhat ironic that aluminum is the best metal
material, it leaves its characteristic signature in
to use because the semiconductor industry
the angle at which it reflects the energy.
recently dumped aluminum in favor of copper –
the better electrical conductor – as it is wiring of
In the field of chemical sensing plasmonics
choice. Of course, it may turn out that some kind
offers the possibility of new technologies that
of alloy will have even better plasmonic
will allow Doctors, anti-terror squads and
properties than either aluminum or copper.
environmental experts to detect chemicals in
quantities as small as a single molecule.
Another classic semiconductor issue that the
researchers will have to address is ‘heat’.
Conclusions:
Chipmakers are constantly striving to ensure that
Plasmonics has
their electronic chips don’t run too hot.
the potential to
Plasmonics also will generate some heat, but the
play a unique
exact amount is not yet known. Even if
and
important
plasmonics runs as hot as electronics, it will still
role
in
have the advantage of higher data capacity in the
enhancing
same space.
processing
Promising applications:
speed of future
Before
all-
plasmonic
chips
the
integrated circuits. The field has witnessed an
explosive growth over the last few years and our
are
developed,
knowledge base in plasmonics is rapidly
expanding. As a result, the role of plasmonic
plasmonics will probably be integrated with
devices on a chip is also becoming more well-
conventional silicon devices. Plasmonic wires
defined. In the past, devices were relatively slow
will act as high band-width freeways across the
and bulky. The semiconductor industry has
busiest areas of the chip. Plasmon printing is a
performed an incredible job in scaling electronic
new approach to lithographic printing that takes
devices to nanoscale dimensions. Unfortunately,
advantage of the resonantly enhanced optical
interconnect delay time issues provide significant
intensity in optical near-field of metallic nano-
challenges toward the realization of purely
particles, and that could enable printing of deep
electronic circuits operating above ~10 GHz. In
sub-wavelength features using conventional
stark contrast, photonic devices possess an
photo-resist and simple visible ultra-violet light
enormous data-carrying capacity (bandwidth).
sources.
Unfortunately, dielectric photonic components
are limited in their size by the laws of
diffraction, preventing the same scaling as in
electronics. Finally, plasmonics offers precisely
what electronics and photonics do not have: the
size of electronics and the speed of photonics.
Plasmonic devices, therefore, might interface
naturally with similar speed photonic devices
and similar size electronic components. For these
reasons, plasmonics may well serve as the
missing
link
between
the
two
device
technologies that currently have a difficult time
communicating. By increasing the synergy
between these technologies, plasmonics may be
able to unleash the full potential of nanoscale
functionality and become the next wave of chipscale technology.
Acknowledgements:

Articles
from
website
http://www.sciencedaily.com

Articles
from
website
http://www.wisegeek.com

Plasmonic technology and its applications
by Dr S S Verma, professor in Dept of
Physics, SLIET, Longolwal, Punjab

Plasmonics, the next chip-scale technology –
Rashid Zia, Anu Chandran and Mark
L
Brongersma from Geballe Laboratory for
Advanced Materials, Stanford University,
Stanford, California USA
End of Document