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Attosecond Physics

Ultrafast signal control

München, 03/14/2014

The future of signal processing: Ferenc Krausz describes the future of information technology

In Zukunft könnten Lichtwellen auf einen Chip treffen, mit dessen Hilfe dann wiederum Strom (grün) mit den Frequenzen der Lichtwellen geschaltet wird (bis zu Petahertz, also 1000 Billionen Schwingungen pro Sekunde). (Bild: Christian Hackenberger)Light waves have the potential to boost the efficiency of conventional electronics by a factor of 100,000. In a review article that appears in “Nature Photonics” on March 14th, Professor Ferenc Krausz, Head of the Institute of Experimental Physics at LMU and Director at the Max Planck Institute for Quantum Optics, and his co-author Professor Mark Stockman of Georgia State University in Atlanta describe how this vision may one day come true. In their scenario, one would exploit the electric field of laser light to control the flow of electrons in dielectric materials, which, in turn, may modulate transmitted light and switch current in electronic circuits at light frequencies.

Light is likely to become the tool of choice for controlling electric currents and data processing. After all, its electric field directs the behavior of electrons, which are the stuff of electric current and encode the information in our computer and communications networks. The ability to manipulate electrons with light would open up a new era by permitting switching rates of 1015 per second, for light waves oscillate at frequencies of that order. But turning this vision into a reality will require essentially perfect control over the properties of light waves.

A 100,000-fold increase in speed
The new issue of Nature Photonics also includes a report on the latest work done by Professor Krausz and his team, in collaboration with Mark Stockman and Vadym Apalkov from GSU. They have shown that the current generated in an insulating material (silica) by the electric field of an intense and ultrashort laser pulse provides information about the precise waveform of the pulse that produced it.

This finding represents the first step towards the realization of a detector that can visualize the shape of light waves, just as an oscilloscope “reproduces” microwaves. This breakthrough means that attosecond technology is at least on course to extend the domain of electron metrology into the optical frequency range. Whether or not this will lead to a corresponding increase in signal processing rates remains an open question. “Our goal is to develop a chip that allows us to switch electric currents on and off at optical frequencies. This would increase rates of information processing by a factor of 100,000, and that is as fast as it gets.”

The published experiments are still in the realm of basic research. But the scientists have begun to breach the limits of conventional electronics and photonics, thus opening the route to a far more efficient, light-based, electronics. (Nature Photonics) Thorsten Naeser