With the growth of computing
technology the need of high performance computers (HPC) has significantly
increased. Optics has been used in computing for a number of years but the main
emphasis has been and continues to be to link portions of computers, for
communications, or more intrinsically in devices that have some optical
application or component (optical pattern recognition etc.)
Optical
computing was a hot research area in 1980’s.But the work tapered off due to
materials limitations that prevented optochips from getting small enough and
cheap enough beyond laboratory curiosities. Now, optical computers are back
with advances in self-assembled conducting organic polymers that promise
super-tiny of all optical chips.
Optical
computing technology is, in general, developing in two directions. One approach
is to build computers that have the same architecture as present day computers
but using optics that is Electro optical hybrids. Another approach is to
generate a completely new kind of computer, which can perform all functional
operations in optical mode. In recent years, a number of devices that can
ultimately lead us to real optical computers have already been manufactured. These
include optical logic gates, optical switches, optical interconnections and
optical memory.
Current
trends in optical computing emphasize communications, for example the use of
free space optical interconnects as a potential solution to remove ‘Bottlenecks’
experienced in electronic architectures. Optical technology is one of the most
promising, and may eventually lead to new computing applications as a
consequence of faster processing speed, as well as better connectivity and
higher bandwidth.
NEED FOR OPTICAL COMPUTING
The
pressing need for optical technology stems from the fact that today’s computers
are limited by the time response of electronic circuits. A solid transmission
medium limits both the speed and volume of signals, as well as building up heat
that damages components.
One
of the theoretical limits on how fast a computer can function is given by
Einstein’s principle that signal cannot propagate faster than speed of light.
So to make computers faster, their components must be smaller and there by
decrease the distance between them. This has resulted in the development of
very large scale integration (VLSI) technology, with smaller device dimensions
and greater complexity. The smallest dimensions of VLSI nowadays are about
0.08mm. Despite the incredible progress in the development and refinement of
the basic technologies over the past decade, there is growing concern that
these technologies may not be capable of solving the computing problems of even
the current millennium. The speed of computers was achieved by miniaturizing
electronic components to a very small micron-size scale, but they are limited
not only by the speed of electrons in matter but also by the increasing density
of interconnections necessary to link the electronic gates on microchips.
The
optical computer comes as a solution of miniaturizing problem. Optical data
processing can perform several operations in parallel much faster and easier
than electrons. This parallelism helps in staggering computational power. For
example a calculation that takes a conventional electronic computer more than
11 years to complete could be performed by an optical computer in a single
hour. Any way we can realize that in an optical computer, electrons are
replaced by photons, the subatomic bits of electromagnetic radiation that make
up light.
