Working Principle of Optical
Computer
The working principle of Optical
Computer is similar to the conventional computer except with some portions that
performs functional operations in Optical mode. Photons are generated by LED’s,
lasers and a variety of other devices. They can be used for encoding the data
similar to electrons.
Design and implementation of
Optical transistors is currently under progress with the ultimate aim of
building Optical Computer. Multi design Optical transistors are being
experimented with. A ninety degree rotating, polarizing screen can effectively
block a light beam. Optical transistors are also made from dielectric materials
that have the potential to act as polarizers. Optical logic gates are slightly
challenging, but fundamentally possible. They would involve one control and
multiple beams that would provide a correct logical output.
Fig. 6 – (a) Optical Network on
Chip (b) Photonic Chip on Circuit
Electrons have one superior
advantage in that, silicon channels and copper wires can be turned and
electrons would follow. This effect can be emulated in Optical Chips using
Plasmonic Nano particles. They are used for turning corners and continue on
their path without major power loss or electron conversions.
Most parts of an Optical chip
resembles any other commercially found computer chip. Electrons are deployed in
the parts that transform or process information. The interconnects however,
have drastic changes. These interconnects are used for information shuttling
between different chip areas. Instead of electron shuttling, which might slow
down when interconnects heat up, light is shuttled. This is because light can
be easily contained and has an advantage of less information loss during
travel.
Researchers are hoping that this
swift communication process might result in the development of exascale
computers i.e. computers that perform billions of calculations every second,
1000 times more processing speed than current speediest systems.
Advantages of Optical Computer
The advantages of Optical
Computer are:
· Optical
computer has several major advantages of high density, small size, low junction
heating, high speed, dynamically scalable and reconfigurable into smaller/
larger networks/ topologies, massive parallel computing ability and AI
applications.
· Apart
from speed, Optical interconnections have several advantages. They are
impervious to electromagnetic interference and are not prone to electrical
short circuits.
· They
offer low-loss transmission and large bandwidth for parallel communication of
several channels.
· Optical
processing of data is inexpensive and much easier than the processing done on
electronic components.
· Since
photons are not charged, they do not readily interact with one another as
electrons. This adds another advantage in that, light beams pass through each
other in full duplex operation.
· Optical
materials have greater accessibility and storage density than magnetic
materials.
Disadvantages of Optical Computer
The disadvantages of Optical
Computer are:
· Manufacturing
Photonic Crystals is challenging.
· Computation
is complex as it involves interaction of multiple signals.
· Bulky
in size.
Future of Optical Computing
We can see interesting
developments in lasers and lights. These are taking over the electronics in our
computers. Optical technology is currently being promoted for use in parallel
processing, storage area networks, Optical Data Networks, Optical Switches,
Biometric and Holographic storage devices at airports.
Processors now contain light
detectors and tiny lasers that facilitate data transmission through Optical
Fiber. Few companies are even developing Optical Processors that use Optical
Switches and laser light to do the calculations. One of the foremost promoters
‘Intel’ is creating an Integrated Silicon Photonics link that is capable of
transmitting 50 Gigabytes per second of uninterrupted information.
It is speculated that future
computers would come without screens where information presentation is made
through a hologram, in the air, and above the keyboard. This kind of technology
is being made possible by the collaboration of researchers and industrial
experts. Also, Optical technology’s most practical use i.e. the ‘Optical
Networking business’ is predicted to reach 3.5 billion dollars from 1 billion
currently.
From
<https://electricalfundablog.com/optical-computer/>
Optical Computing: Solving Problems at the Speed of Light
According to Moore’s law
—actually more like a forecast, formulated in 1965 by Intel co-founder Gordon
Moore— the number of transistors in a microprocessor doubles about every two
years, boosting the power of the chips without increasing their energy
consumption. For half a century, Moore’s prescient vision has presided over
the spectacular progress made in the world of computing. However, by 2015, the
engineer himself predicted that we are reaching a saturation point in
current technology. Today, quantum computing holds out hope for a new
technological leap, but there is another option on which many are pinning their
hopes: optical computing, which replaces electronics (electrons) with
light (photons).
The end of Moore’s law is a
natural consequence of physics: to pack more transistors into the same space
they have to be shrunk down, which increases their speed while simultaneously
reducing their energy consumption. The miniaturisation of silicon
transistors has succeeded in breaking the 7-nanometre barrier, which used
to be considered the limit, but this reduction cannot continue indefinitely.
And although more powerful systems can always be obtained by increasing the
number of transistors, in doing so the processing speed will decrease and the
heat of the chips will rise.
THE HYBRIDIZATION OF ELECTRONICS
AND OPTICS
Hence the promise of optical
computing: photons move at the speed of light, faster than electrons in a wire.
Optical technology is also not a newcomer to our lives: the vast global traffic
on the information highways today travels on fibre optic channels,
and for years we have used optical readers to burn and read our CDs, DVDs and
Blu-Ray discs. However, in the guts of our systems, the photons coming through
the fibre optic cable must be converted into electrons in the microchips, and
in turn these electrons must be converted to photons in the optical readers,
slowing down the process.
The overhead view
of a new beamsplitter for silicon photonics chips that is the size of
one-fiftieth the width of a human hair. Credit: Dan
Hixson/University of Utah College of Engineering
Thus, it can be said that our
current technology is already a hybridization of electronics and optics. “In
the near-term, it is pretty clear that hybrid optical-electronic systems will
dominate,” Rajesh Menon, a computer engineer at the University of Utah, tells
OpenMind. “For instance, the vast majority of communications data is channelled
via photons, while almost all computation and logic is performed by electrons.”
And according to Menon, “there are fundamental reasons for this division of
labour,” because while less energy is needed to transmit information in the
form of photons, the waves associated with the electrons are smaller; that is,
the higher speed of photonic devices has as its counterpart a larger size.
This is why some experts see
limitations in the penetration of optics in computing. For Caroline Ross, a
materials science engineer at the Massachusetts Institute of Technology (MIT),
“the most important near-term application [for optics] is communications — managing
the flow of optical data from fibres to electronics.” The engineer, whose
research produced an optical diode that facilitates this task, tells OpenMind
that “the use of light for actual data processing itself is a bit further out.”
THE LASER TRANSISTOR
But although we are still far
from the 100% optical microchip —a practical system capable of computing only
by using photons— advances are increasing the involvement of photonics in
computers. In 2004, University of Illinois researchers Milton Feng and Nick
Holonyak Jr. developed the concept of the laser transistor, which replaces one
of the two electrical outputs of normal transistors with a light signal in the
form of a laser, providing a higher data rate.
For example, today it is not
possible to use light for internal communication between different components
of a computer, due to the equipment that would be necessary to convert the
electrical signal to optical and vice versa; the laser transistor would make
this possible. “Similar to transistor integrated circuits, we hope the
transistor laser will be [used for] electro-optical integrated circuits for
optical computing,” Feng told OpenMind. The co-author of this breakthrough is
betting on optical over quantum computing, since it does not require the icy
temperatures at which quantum superconductors must operate.
Graduate students
Junyi Wu and Curtis Wang and Professor Milton Feng found that light stimulates
switching speed in the transistor laser. Credit: L. Brian Stauffer
Proof of the interest in this
type of system is the intense research in this field, which includes new
materials capable of supporting photon-based computing. Among the challenges
still to be met in order to obtain optical chips, Menon highlights the
integration density of the components in order to reduce the size, an area in
which his laboratory is a pioneer, as well as a “better understanding of
light-matter interactions at the nanoscale.”
Despite all this, we shouldn’t be
overly confident that a photonic laptop will one day reach the hands of
consumers. “We don’t expect optical computing to supplant electronic
general-purpose computing in the near term,” Mo Steinman, vice president of
engineering at Lightelligence, a startup from the photonics lab run by Marin
Soljačić at MIT, told OpenMind.
Present and future of photonics
However, the truth is that
nowadays this type of computing already has its own niches.
“Application-specific photonics is already here, particularly in data centres
and more recently in machine learning,” says Menon. In fact, Artificial
Intelligence (AI) neural networks are being touted as one of its great
applications, with the potential to achieve 10 million times greater efficiency
than electronic systems. “Statistical workloads such as those employed in AI
algorithms are perfectly suited for optical computing,” says Steinman.
Thus, optical computing can solve
very complex network optimization problems that would take centuries for
classical computers. In Japan, the NTT company is building a huge optical
computer that encloses five kilometres of fibre in a box the size of a room,
and will be applied to complicated power or communications networks enhancement
tasks.
A photonic
integrated circuit. Credit: JonathanMarks
“Looking ahead, we believe we can
leverage the ecosystem created by optical telecommunications in the areas of
integrated circuit design, fabrication, and packaging, and optimize for the
specific operating points required by optical computing,” Steinman predicts.
However, he admits that moving from a prototype to full-scale manufacturing
will be a difficult challenge.
In short, there are reasons for
optimism about the development of optical computing, but without overestimating
its possibilities: when computer scientist Dror Feitelson published his
book Optical
Computing (MIT Press) in 1988, there was talk of a new field that
was already beginning to reach maturity. More than 30 years later, “optical
computing is still more of a promise than a mainstream technology,” the author
tells OpenMind. And the challenges still to be overcome are
compounded by another stumbling block: technological inertia.
Feitelson recalls the warning issued in those days by IBM researcher Robert
Keyes: with the enormous experience and accumulated investment in electronics
that we already know, “practically any other technology would be unable to
catch up.”
From
<https://www.bbvaopenmind.com/en/technology/future/optical-computing-solving-problems-at-the-speed-of-light/>
Optical computers light up the horizon
Optical chips will
power our future datacenters and supercomputers. Electronic chips can now have
a layer of optical components, like lasers and switches, added to it, to
increase their computing power. Credit: Martijn Heck, Aarhus University
Since their
invention, computers have become faster and faster, as a result of our ability
to increase the number of transistors on a processor chip.
Today, your
smartphone is millions of times faster than the computers NASA used to put the
first man on the moon in 1969. It even outperforms the most famous
supercomputers from the 1990s. However, we are approaching the limits of this
electronic technology, and now we see an interesting development: light and
lasers are taking over electronics in computers.
Processors can now
contain tiny lasers and light detectors, so they can send and receive data
through small optical fibres, at speeds far exceeding the copper lines we
use now. A few companies are even developing optical processors: chips that use
laser light and optical switches, instead of currents and electronic
transistors, to do calculations.
So, let us first
take a closer look at why our current technology is running out of steam. And
then, of course, answer the main question: when can you buy that optical
computer?
Moore's Law is
dying
Computers work
with ones and zeros for all their calculations and transistors are the little
switches that make that happen. Current processor chips, or integrated
circuits, consist of billions of transistors. In 1965, Gordon Moore, founder of
Intel, predicted that the number of transistors per chip would double every two
years. This became known as Moore's Law, and after more than half a century, it
is still alive. Well, it appears to be alive...
In fact, we are
fast reaching the end of this scaling. Transistors are now approaching the size
of an atom, which means that quantum mechanical effects are becoming a
bottleneck. The electrons, which make up the current, can randomly disappear
from such tiny electrical components, messing up the calculations.
Moreover, the
newest technology, where transistors have a size of only five nanometers, is now
so complex that it might become too expensive to improve. A semiconductor fabrication plant for this five-nanometer chip
technology, to be operational in 2020, has already cost a steep 17 billion US
dollars to build.
Computer
processor chips have plateaued
Looking more
closely, however, the performance growth in transistors has been declining.
Remember the past, when every few years faster computers hit the market? From
10 MHz clock speed in the 80s, to 100 MHz in the 90s and 1 GHz in 2000? That
has stopped, and computers have been stuck at about 4 GHz for over 10 years.
Of course with
smart chip design, for example using parallel processing in multi-core
processors, we can still increase the performance, so your computer still works
faster, but this increased speed is not due to the transistors themselves.
And these gains
come at a cost. All those cores on the processor need to communicate with each
other, to share tasks, which consumes a lot of energy. So much so that the
communication on and between chips is now responsible for more than half of the
total power consumption of the computer.
Since computers
are everywhere, in our smartphone and laptop, but also in datacenters and the
internet, this energy consumption is actually a substantial amount of our
carbon footprint.
For example, there
are bold estimations that intense use of a smartphone connected to the Internet
consumes the same amount of energy as a fridge. Surprising, right? Do not worry
about your personal electricity bill, though, as this is the energy consumed by
the datacenters and networks. And the number and use of smartphones and other
wearable tech keeps growing.
Fear not:
lasers to the rescue
So, how can we
reduce the energy consumption of our computers and make them more sustainable?
The answer becomes clear when we look at the Internet.
In the past, we
used electrical signals, going through copper wires, to communicate. The
optical fibre, guiding laser light, has revolutionised communications, and has
made the Internet what it is today: Fast and extending across the entire world.
You might even have fibre all the way to your home.
We are using the
same idea for the next generation computers and servers. No longer will the
chips be plugged in on motherboards with copper lines, but instead we will use
optical waveguides. These can guide light, just like optical fibres, and are
embedded into the motherboard. Small lasers and photodiodes are then used to
generate and receive the data signal. In fact, companies like Microsoft are
already considering this approach for their cloud servers.
Optical chips
are already a reality
Now I know what
you're thinking around about now:
"But wait a
second, how will these chips communicate with each other using light? Aren't
they built to generate an electrical current?"
Yes, they are. Or,
at least, they were. But interestingly, silicon chips can
be adapted to include transmitters and receivers for light, alongside the
transistors.
Researchers from the Massachusetts Institute of
Technology in the US have already achieved this, and have now started a company
(Ayar Labs) to commercialise the technology.
Here at Aarhus
University in Denmark we are thinking even further ahead: If chips can
communicate with each other optically, using laser light, would it not also
make sense that the communication on a chip—between cores and transistors—would
benefit from optics?
We are doing
exactly that. In collaboration with partners across Europe, we are figuring out
whether we can make more energy-efficient memory by writing the bits and bytes
using laser light, integrated on a chip. This is very
exploratory research, but if we succeed, it could change future chip technology as early as 2030.
The future:
optical computers on sale in five years?
So far so good,
but there is a caveat: Even though optics are superior to electronics for
communication, they are not very suitable for actually carrying out
calculations. At least, when we think binary—in ones and zeros.
Here the human
brain may hold a solution. We do not think in a binary way. Our brain is not
digital, but analogue, and it makes calculations all the time.
Computer engineers
are now realising the potential of such analogues, or brain-like, computing,
and have created a new field of neuromorphic computing, where they try to mimic
how the human brain works using electronic chips.
And in turns out
that optics are an excellent choice for this new brain-like way of computing.
The same kind of
technology used by MIT and our team, at Aarhus University, to create optical
communications between and on silicon chips, can also be used to make such
neuromorphic optical chips.
In fact, it has
already been shown that such chips can do some basic speech recognition. And two start-ups in the US, Lightelligence and Lightmatter, have now
taken up the challenge to realise such optical chips for
artificial intelligence.
Optical chips are
still some way behind electronic chips, but we're already seeing the results and
this research could lead to a complete revolution in computer power. Maybe in
five years from now we will see the first optical co-processors in
supercomputers. These will be used for very specific tasks, such as the
discovery of new pharmaceutical drugs.
But who knows what
will follow after that? In ten years these chips might be used to detect and
recognise objects in self-driving cars and autonomous drones. And when you are
talking to Apple's Siri or Amazon's Echo, by then you might actually be
speaking to an optical computer.
While the 20th
century was the age of the electron, the 21st century is the age of the photon
– of light. And the future shines bright.
From
<https://phys.org/news/2018-03-optical-horizon.html>
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all discussed seminar topics list click here Index.
…till
next post, bye-bye and take care.
