Latest News

Liquid light switch could enable more powerful electronics

Researchers from the University of Cambridge have built an energy-efficient switch which uses the interplay of electricity and a liquid form of light, in semiconductor microchips. The device could form the foundation of future signal processing and information technologies, making electronics more efficient.

The miniature electro-optical switch can change the spin – or angular momentum – of a liquid form of light by applying electric fields to a semiconductor device a millionth of a metre in size. The researchers (led by Jeremy Baumberg from Cambridge’s NanoPhotonics Centre) were able to demonstrate how to bridge the gap between light and electricity, which could enable the development of faster and smaller electronics.

In order for technology to process information, electrical charges are moved around on semiconductor chips. To transmit information, light flashes are sent down optical fibres. However, current methods of converting between electrical and optical signals are both inefficient and slow, and therefore researchers have been searching for ways to incorporate the two.

The University of Cambridge researchers have built a switch which utilises a new state of matter called a Polariton Bose-Einstein condensate in order to mix electric and optical signals, while using little energy. These condensates are generated by trapping light between mirrors spaced a few millionths of a metre apart, and letting it interact with thin slabs of semiconductor material, creating a half-light, half-matter mixture known as a polariton.

Putting many polaritons in the same space can induce condensation and the formation of a light-matter fluid which spins clockwise (spin-up) or anticlockwise (spin-down). By applying an electric field to this system, the researchers were able to control the spin of the condensate and switch it between up and down states. The polariton fluid emits light with clockwise or anticlockwise spin, which can be sent through optical fibres for communication, converting electrical to optical signals.

“The polariton switch unifies the best properties of electronics and optics onto one tiny device that can deliver at very high speeds while using minimal amounts of power,” said Alex Dreismann, lead author of the team’s research paper.

“We’re reaching the limits of how small we can make transistors, and electronics based on liquid light could be a way of increasing the power and efficiency of the electronics we rely on,” added co-author Hamid Ohadi.

While the prototype device works at cryogenic temperatures, the researchers are developing other materials that can operate at room temperature, enabling the device to be commercialised.

Send this to a friend