Thursday, November 27, 2008

Disadvantages of Optical Computing

Although there are many positive aspetcs about optical computers, there are also some disadvantages.

Expensive Components

Parts for conventional computers are produced in plants whose only job is to manufacture these parts therefore, the price is low mainly do to mass production. Optical components on the other hand there are not any manufacturers the specialize in the production of optical components and as a result, the price is high.

Components are not the "right size"

In contrast with conventional computer parts, optical components are of larger magnitude. Researchers have not yet been able to create optical components small enough to assemble a motherboard.

Manufacturing Problems

For the computer to work properly, the miniaturized components need to be manufactured exactly. As aforementionned, this has not yet been achieved. Even the slightest of deviations can cause the light beams (lasers) to divert resulting in massive problems. Therefore, it can be concluded that the production process is quite costly.


Conventional computers are assembled accordingly with the Von Neumann archictecture. Application software and operating systems are built around this architecture. In contrast, optical computers are put together according to a different architecture because of the system's parallelism. As a result, opearating systems such as Microsoft Windows may not be able to function properly or may not even function at all.


Monday, November 24, 2008

Advantages of Optical Computing

All of the follwing are positive aspects of optical computers.

Higher performance

Although optical computers are still in their early stages and cannot yet be compared to conventional computers, it still is safe to say that they have a higher processing speed. There are two reason for this. First, as discussed previously, metallic wires reduce the transmission speed. Second, in the seminar (referenced further down), the author states that nothing is faster than the speed of light.

Higher parallelism

This is achieved in two ways:

  1. "Increase the amount of data which is sent through bus systems and computed in the CPU at each time." (

  2. Data paths can cross without interference.

Less consumption

Modern day computers consume a lot of energy. In the seminar, the speaker states that computers require over 80 watts in idle state, 120 watts during normal use and 250 in performance mode and all of this energy is not used efficiently. Here is a calculation example:

"A computer runs every day around eight hours in normal use and one kilowatt hour costs 0,15 €. That means that the CPU consumes around 350 kilowatt hours a year. Consequently 53 € of energy costs are generated only by the CPU. All components of a loaded high performance PC (without monitor and periphery) consume within the same time even 1100 kilowatt hours (165 €)."

Example retreived from:

Less heat is released

As previously mentionned, optical computers function with the use of lasers. These do not radiate much heat, depending on the application. Moreover, compared to conventional computers, optical computers do not require a processor airing therefore, they could be smaller and do not need free space for airing. As a consequence, the probability of a fire occuring due to overheating are significantly reduced.

Less noise

Conventional computers often produce a lot of noise due to the rotating fan. Because optical computers do not have fans for airing, the noise factor is also reduced significantly.

More flexibility in layout

Conventional computers are usually built in the form of a rectangular box (or in the form of a laptop). The reason for this is the speed of the electric connections. "Using optical components the distance of communication does not matter. Once the signal is in an optical fiber it does not matter whether the signal runs 1 meter or 1000 meters. Because of the low damping long-range communication is possible. Still the data rate is very high and there is no crosstalk.
So the optical computer technology has the potential to change the shape and layout of computers fundamentally. The components of one computer can be spread across a car, a building or even a city with almost no loss in performance. Consequently the server/client and the peer-to-peer architectures could be advanced. Many clients, terminals or even single components can be connected optically and consequently allow higher ranges." (

Reduced loss in communication

Nowadays, communication is often transmitted through electric wires or radio frequency thus reducing the range in the communocatio process. Optical computers use optical wires to transmit data. These have a higher bandwith therefore which leads to higher performance.


This information was retreived from a seminar on Information Technology and its trends:

Other sources include:,9171,997259,00.html

Sunday, November 23, 2008

Optical Computers Take Over the World?

What of optical computers?

It is evident that optical computers will replace electronic computers in the near future. But why? The reason is quite simple. According to Moore's Law, the number of transistors in a computer chip doubles every 18 months. Unfortunately, this doubling cannot be sustained forever. Therefore, traditional transistors can no longer keep up. Moreover, it was found that metallic wires limit the speed of the transmission. "Resistance per unit length in the chip is being increased, causing more power usage and excess heating." This is not the case with optical computers.

What will optical computers replace?

Simple. They will replace silicon computers. As mentioned above, in the case of optical computers light beams can pass through one another, making possible three-dimensional microprocessors. (see image) It has been said that these computers would be the size of a car. Not very handy for personal use at home! Moreover, we have also seen that the standard trackball mouse has been replaced with the optical mouse.


Saturday, November 22, 2008

Optical Computing 101: The Basics

What is optical computing?

Definition : An optical computer is a computer that uses light (photons) instead of electricity (electrons) to manipulate, store and transmit data.

The goal of this type of computer is to create a computer that is more powerful and that has greater capabilities than regular electric computers. Unfortunately, optical computers have not made it past the prototype stage. The best example to give of an optical device would be an optical mouse.

There are two types of optical computers:

  • Electro-Hybrid Optical computers

  • Pure Optical computers

Electro-Optical Hybrid

As its name would suggest, this type of optical computer uses both optics and electricity to transmit, store and manipulate data. It reads and directs data from the processor with the use of optical fibers and electric parts. Because optical computers use photons (light particles) instead of electrons (electric particles), light pulses send information instead of voltage packets. With the use of lasers, this information is changed from binary code to light pulses. And finally, the information in detected and changed back into binary code.

Pure Optical

This type of optical computer uses multiple frequencies to send the information through the computer as light waves. Unlike the Electro-Optical model, there is no use of electricity; it strictly uses optics to transmit data. Therefore, there is no need to convert the information from binary to optical, which increases the speed of the processing.