How the slowing of light could benefit fibre-optic communications, that is speeding up telecommunications networks, is discussed. Mechanisms for the potential telecoms application are briefly explained - resynchronisation and regeneration processes.
Fast or slow light propagation means that the group velocity of a quasi-monochromatic light pulse propagating in a resonant medium can be significantly faster or slower than the light speed in a vacuum. Since the end of the last century and the beginning of this century, studies on this subject have attracted a great deal of interest. Remarkable progress has been achieved, based on various nonlinear optical interactions in resonant media. The fundamental research on this subject can enrich our understanding of special relativity and causality in physics. On the other hand, those mechanisms and techniques developed for fast and slow light propagation have provided the potential for many future applications, such as optical buffers and variable delay lines for optical networks, optical computing, optical telecommunications, optical data storage, and signal processing.
In the last 10 years, technology that can encode information onto pulses of light and then send it around the globe through ultra-thin glass fibres has revolutionized the way we communicate. With the pulses travelling at speeds of up to 200 000kms-1, and suffering very little attenuation, someone in New York can have a telephone conversation with someone in Bangalore almost in real time, even though they are some 13 300 km apart. This is an excellent example of technology bringing people closer together and leading to a truly global economy.