Silicon nanoantennas for optical computers

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A team of physicists from ITMO University, MIPT, and the University of Texas at Austin has developed a nanoantenna that scatters light in a particular direction depending on the intensity of incident radiation. The researchers claim the findings will help develop flexible optical information processing in telecommunication systems.

"Existing optical nanoantennas can control light in a wide range. However, this ability is usually embedded in their geometry and the materials they are made of, so it is not possible to configure these characteristics at any time," said postgraduate student Denis Baranov at MIPT. "The properties of our nanoantenna can be dynamically modified. When we illuminate it with a weak laser impulse, we get one result, but with a strong impulse, the outcome is completely different.”

To rotate the radiation pattern of the nanoantenna, the authors used the mechanism of plasma excitation in silicon.

The nanoantenna is a dimer – two silicon nanospheres of unequal diameters. Irradiated with a weak laser beam, this antenna scatters the light sideways due to its asymmetric shape.

By accurately choosing the relative size of both particles in combination with the duration and intensity of the incident beam, it is possible to make the size of the particles virtually the same, which enables the antenna to bounce the light beam forward.

This provides an opportunity to deflect weak and strong incident impulses in different directions.

“Our device will be able to distribute a signal into two optical channels within a short space of time, which is extremely important for modern telecommunication systems," senior researcher at ITMO University, Sergey Makarov, concluded.