Could light drive future transistors?

Light waves might be able to drive future transistors, according to research conducted by the Max-Planck Institute of Quantum Optics (MPQ), the Ludwig-Maximilians-Universität (LMU) and theorists from the University of Tsukuba.

Light waves oscillate with petahertz frequencies, the team notes, adding that, in principle, future electronics could reach this speed. But the approach is said to require a better understanding of the sub-atomic electron motion induced by the ultrafast electric field of light. The researchers say they have combined experimental and theoretical techniques which provide direct access to this motion for the first time. MPQ physicists have already determined that it is possible to manipulate the electronic properties of matter at optical frequencies. In a follow-up experiment, the researchers shot extremely strong laser pulses of a few femtoseconds duration onto silicon dioxide glass. Because the light pulse only includes one single strong oscillation cycle of the field, the electrons are moved left and right only once. Measurements showed that electrons react to the incoming light with a delay of 10x10-18s. Since it is possible to measure this energy exchange within one light cycle, the team says the parameters of the light-matter interaction can be understood and optimised. The more reversible the exchange and the smaller the amount of energy left behind after the light pulse is gone, the more the interaction is suited to light field-driven electronics. To identify the best set of experimental parameters, the experiments were backed up by a simulation method developed at the University of Tsukuba, where the theoreticians used the K computer – the fourth fastest supercomputer – to model electron movement inside solids with unprecedented accuracy. At certain field strengths, the energy transferred from the field to the solid during the first half of the pulse cycle is believed to be emitted almost completely during the second half of the cycle. These findings suggest that a switching medium for light driven electronics would not overheat and that the ’cool relationship’ between glass and light might provide an opportunity to accelerate electronic signal and data processing dramatically.

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