Optical computing promises to be much faster than electrical chips.
A prolific worldwide team of researchers, headquartered at Texas A&M University at Qatar (TAMUQ), using theoretical physics and mathematics to model various signal processing systems in an effort to design better, faster and more powerful computer systems, have recently published their 100th paper on the topic.
The group, headed by Professor Milivoj Belic, is developing an all-optical information system using novel concepts of nonlinear photonics. The way that signals (information) are transported from one place to another is largely based on electronics – chips and transistors which work on currents and require electronics to make them function. On the other hand, it is quicker and more efficient to use fibre optics for signal transportation. This ‘fibre transportation’ requires in-depth knowledge of photonics – the science of light.
At regular intensities, light can be described as a linear system, which is to say there is a proportional relationship between the cause and effect. But at very high intensities, such as those used with laser-generated pulse signals, the systems stop behaving in a simple way and become ‘non-linear’. This may sound esoteric, but understanding how pulses (or ‘light bullets’) propagate through media, and how they evolve, involves some mathematics you may have encountered before; partial differential equations, and especially wave equations.
The combination of electrical and optical systems in information transmission means there are many different systems to model, particularly when it comes to how they interact with each other. The ultimate goal, says Dr Belic, would be all-optical information processing, “there would be no need to change from one way of coding information (using electronics) to another (using optics) if they were all optical. This transformation always introduces a time delay and that time delay is avoided in all optical information processing. But this is a holy grail. In time it will be resolved.”
An all-optical processing system also involves application of another concept known as polariton plasmonic physics. When you are dealing with light at very small scales, the wavelength of light must be taken into account – and it is not insignificant at this scale. Electronic chips can be smaller than the wavelength of light, so quantum mechanics (QM) become a factor. It becomes necessary to couple light with QM devices and one way to do that is to excite plasmonic modes on metallic surfaces and generate surface plasmonic polaritons. This is an active field of research for the mutli-center, multinational group.
Professor Belic pointed out that this kind of largely theoretical research is sometimes ignored in developing countries as they prefer to concentrate on large scale engineering and healthcare issues, but he was keen to emphasise the support that both QNRF and TAMUQ have afforded him and his team as they develop new applications of mathematics and physics which may one day transform computing for the whole world.
Light bullets, fractional vortices, and nonlocal solitons for all-optical information transmission in photonic crystals, dispersion-managed systems, and distributed fibers