Optical Computers

Optical computer

An optical computer (also called a photonic computer) is a device that uses the photons in visible light or infrared (IR) beams, rather than electric current, to perform digital computations. An electric current flows at only about 10 percent of the speed of light. This limits the rate at which data can be exchanged over long distances, and is one of the factors that led to the evolution of optical fiber. By applying some of the advantages of visible and/or IR networks at the device and component scale, a computer might someday be developed that can perform operations 10 or more times faster than a conventional electronic computer.
Visible-light and IR beams, unlike electric currents, pass through each other without interacting. Several (or many) laser beams can be shone so their paths intersect, but there is no interference among the beams, even when they are confined essentially to two dimensions. Electric currents must be guided around each other, and this makes three-dimensional wiring necessary. Thus, an optical computer, besides being much faster than an electronic one, might also be smaller.

Some engineers think optical computing will someday be common, but most agree that transitions will occur in specialized areas one at a time. Some optical integrated circuits have been designed and manufactured. (At least one complete, although rather large, computer has been built using optical circuits.) Three-dimensional, full-motion video can be transmitted along a bundle of fibers by breaking the image into voxels. Some optical devices can be controlled by electronic currents, even though the impulses carrying the data are visible light or IR.
Optical technology has made its most significant inroads in digital communications, where fiber optic data transmission has become commonplace. The ultimate goal is the so-called photonic network, which uses visible and IR energy exclusively between each source and destination. Optical technology is employed in CD-ROM drives and their relatives, laser printers, and most photocopiers and scanners. However, none of these devices are fully optical; all rely to some extent on conventional electronic circuits and components.

























WORKING:
Optical fibers are small glass wires used to send light pulses. They are basically made up of a center glass core, a cladding that makes sure the light doesn’t escape the core, and a buffer coating which protects the inside fibers. When the light enters the core, it is reflected off the walls, which are mirror-lined so the light continues all the way down the fiber. The process of the light reflecting down the fiber is called total internal reflection.
Because optical fibers transmit light, the transfer speed is extremely fast; a great amount faster than that of the copper wires we use today. Also, when sending information over copper wires, it must put the data in small groups called packets. Copper wires can only send one of these packets at a time because the electrical signals cannot run parallel. Light, on the other hand, has no problem with having other data run parallel with it. This means you can send and receive vast amounts of data at the same time.
Optical Fibers also have other advantages, for example, optical wires are cheaper, thinner (which lets you have a higher carrying capacity than copper wires), more power efficient, have less signal degradation, clearer signals, are optimal for carrying digital signals, lightweight, and flexible. Along with these, optical fibers can also help benefit many occupations such as medical imaging, mechanical imaging, and even in plumbing to examine the sewer lines.



















































COMPARITION:











Smaller, more compact computers are often faster because computation time depends on shorter connections between components. In the search for speed, computer chips have grown ever smaller: it is estimated that the number of transistor switches that can be put onto a chip doubles every 18 months. It is now possible to fit 300 million transistors on a single silicon chip, and some scientists have predicted that in the next few decades computer technology will have reached the atomic level.
Up:Magnification of an Intel i4004 microprocessor chip. Photo copyright: National High Magnetic Field Laboratory, Florida State University.
But more transistors mean the signals have to travel a greater distance on thinner wires. As the switches and connecting wires are squeezed closer together, the resulting crosstalk can inadvertently cause a digital signal to change from a 1 to a 0. Scientists are working on developing newer, better insulators to combat this problem. But optical computers wouldn't need better insulators because they don't experience crosstalk. The thin-films used in electro-optic computers would eliminate many such problems plaguing electronics today.
"The thin-films allow us to transmit information using light. And because we're working with light, we're working with the speed of light without generating as much heat as electrons," says Frazier. "We can move information faster than electronic circuits, and without the need to remove damaging heat."

up: Blue and red lasers reflecting off mirrors. Photo Credit: Department of Energy/Coherent Inc Laser Group.
Multiple frequencies (or different colors) of light can travel through optical components without interference, allowing photonic devices to process multiple streams of data simultaneously. And the optical components permit a much higher data rate for any one of these streams than electrical conductors. Complex programs that take 100 to 1,000 hours to process on modern electronic computers could eventually take an hour or less on photonic computers.











APPLICATION:
 we can use this computer in VIRTUAL REALITY

We can create a 3-D picture using this computer.



 The system uses two computer-controlled infrared lasers to trace its 3-D picture inside a cube of special laminated glass, much as the electron beam from a cathode ray tube traces a 2-D image on a television screen. The energy generated at the point where the invisible laser beams intersect makes a single point of the glass glow with visible light—a precise point like video screen pixel seemingly suspended in space. “This allows you to address a pixel anywhere inside a three-dimensional volume, and then by scanning rapidly, you can draw three-dimensional images.

 It can also be used in MEDICAL SIGNIFICANCE




 This computer also used by ARMY

The computer used in ARMY required very high speed execution because they want quick response from the computer PROCESSOR”. on what ever instruction given by commando. So, in army application we can use this type of computer. They are given idea that “We require this type of operation”. So, the manufactures make that operation related “OPTICAL

















HOLLOW GRAPHIC MEMORY:
When Optical Computers are available, a new type of storage device will be used in the new computers. The new Holographic hard drives will store massive amounts of information in a sugar cube sized area. They will be able to do this by storing data in hologram form. This will be achieved using a precise technique of laser shining, as shown in the diagram to the right. A blue-green argon laser will be shined through a beam splitter. The original beam, which will have been split into a signal beam and a reference beam, will take different paths towards a lithium-niobate crystal. The signal beam will be reflected by a mirror into a spatial light modulator (SLM), which is a liquid crystal display (LCD) that shows pages of raw binary data as clear and dark boxes. The information from the page of binary code is carried by the signal beam around to the light-sensitive crystal. Meanwhile, the reference beam will take another path to the crystal. When the two beams meet, the interference created between them will be stored in a specific area of the crystal, as a hologram.


LIMITATION:

The Limitation is only that it is not still general purpose computer. So it is made for only particular task. Whatever task is given based on this manufacture design the processor. And it will perform that much operation only.

















































CONCLUSION:
Currently, no true optical computers yet exist. The problems of design seem to stem from eliminating the conversion from photons to electrons and back. This conversion is necessary now because we don't have all-optical versions of all the myriad switching devices required by a computer.

In conclusion, technology is always changing, and computer technology will soon take a drastic change too. Optics opens new doors to the computer world that people used to just dream about. From face recognition to artificial intelligence, optics could easily make these practices trouble-free. Optics are already being used around the world for various applications, and the future looks very promising