15-09-2016, 10:23 AM
1454565615-opticalcomputingFINAL.ppt (Size: 783 KB / Downloads: 4)
Introduction
Optical computing was a hot research area in 1980’s. But the work tapered off due to materials limitations.
Using light, instead of electric power, for performing computations.
This choice is motivated by several features that light has:
It is very fast.
It can be easily manipulated (divided, transported, delayed, split, etc)
It is very well suited for parallelization.
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.
Why we Use Optics for Computing?
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”.
To make computers faster, their components must be smaller and there by decrease the distance between them.
Optical computing can solve miniaturization problem.
Optical data processing can be performed in parallel.
In optical computing, the electrons are replaced by photons
VCSEL (VERTICAL CAVITY SURFACE EMITTING LASER)
VCSEL(pronounced‘vixel’)is a semiconductor vertical cavity surface emitting laser diode that emits light in a cylindrical beam vertically from the surface of a fabricated wafer.
But rather than reflective ends, in a VCSEL there are several layers of partially reflective mirrors above and below the active layer.
Layers of semiconductors with differing compositions create these mirrors, and each mirror reflects a narrow range of wavelengths back in to the cavity in order to cause light emission at just one wavelength.
SMART PIXEL TECHNOLOGY
Smart pixel technology is a relatively new approach to integrating electronic circuitry and optoelectronic devices in a common framework.
Here, the electronic circuitry provides complex functionality and programmability.
While the optoelectronic devices provide high-speed switching and compatibility with existing optical media.
Arrays of these smart pixels leverage the parallelism of optics for interconnections as well as computation..
WDM (WAVELENGTH DIVISION MULTIPLEXING)
Wavelength division multiplexing is a method of sending many different wavelengths down the same optical fiber.
WDM can transmit up to 32 wavelengths through a single fiber, but cannot meet the bandwidth requirements of the present day communication systems.
Nowadays DWDM (Dense wavelength division multiplexing) is used. This can transmit up to 1000 wavelengths through a single fiber. That is by using this we can improve the bandwidth efficiency.