Chemistry Makes Light Work

That computer game of yours might just get a little light-hearted boost if you could do something special to upgrade your PC. When your electrons just can't keep up, it may be time to give your computer some light chips. Enter Optics, Optoelectronics, and Photonics (OOPS!). Some combination of these will be the way of the future when it comes to digital computing. Optics, of course, uses lenses, prisms, and mirrors to manipulate light. In optoelectronics, an optical (light) input is converted to an electrical output, or an electrical input is converted to an optical output. Photonics treds much more lightly. A photonic device uses no electrical components at all: optical outputs are controlled by optical inputs. Professor M. Andrews at McGill University in Montreal is working on making optical wires for optical computers.

A conventional computer works by piping electrons around on silicon chips in patterns of micron-sized wires that make up integrated circuits. However, optical computers make use of optical integrated circuits which instead will pipe laser light around in patterns of transparent, very thin optical conductors called wave guides. Optical wires are one form of wave guide. Organic dye molecules can be designed to respond to laser light in such a way as to cause light waves to be in phase or out of phase. Constructive (additive effect on waves) or destructive (cancels effects of waves) interference of the light waves can then be used to give a logical 'one' or 'zero' that form the basis of the logical bits, '1' and '0', for conventional computers.

A similar program by Chemistry Professor A. Natansohn at Queen's University, Kingston and Physics Professor, P. Rochon at the Royal Military College, Kingston is aimed at the development of optical memory . Everyone is familiar with compact disks (CDs). In a typical CD, the information is inscribed as very small holes on the surface of a polymer material. A hole is a '1' while the uninscribed surface is a '0', thus permitting binary memory inscription. The main disadvantage of compact disks as memory devices is the Read Only Memory (ROM) or Write Once Read Many Times (WORM). This means that only one set of information can be written. The materials developed in Kingston will be of the Random Access Memory (RAM) type (similar to a cassette tape), on which you can write, read, erase, and rewrite as many times as you wish. How does it work? Well, first of all, the difference from a compact disk is that no chemical or physically permanent change takes place on the polymer surface of the RAM. Instead, the polymer material chosen contains rod-like groups which are randomly distributed ('0' state). When exposed to polarized light, the rods align and remain aligned indefinitely ('1' state) until they are illuminated with another type of polarized light that reverts the rods to a totally random distribution (back to the '0' state).

How's that for light work?