New technology converts radio waves into light signals

Thursday 06 Mar 14
Researchers from DTU and the Niels Bohr Institute have developed a new technology that enables the detection of very faint radio signals. The technology may prove significant in improving signals for use in medical imaging, astronomy, navigation and communication.

Flickering and poor signals are often the result when weak radio signals and interference from electronic equipment prevent us from receiving clear radio transmissions. However, researchers from DTU Nanotech and the Niels Bohr Institute have now developed a new method for picking up much fainter radio signals than was previously possible.

The new technology may prove extremely useful in a wide range of applications including astronomy, navigation, communication and medical imaging, by picking up faint cosmic microwave radiation from the universe, improving GPS and Wi-Fi connections, and enabling more detailed images from MRI scanners. The ground-breaking findings have just been published in Nature.

Hardly any noise
“The new concept contains enormous potential. Converting radio waves to light signals, that are subsequently transferred and analysed using optical tools, ensures that we add hardly any noise to the detected signal. This is a completely new approach that we hope will break new ground,” relates Associate Professor Silvan Schmid from DTU Nanotech.

The research project was launched three years ago, when physicists from Eugene Polzik’s group at the Niels Bohr Institute contacted DTU Nanotech to ask for assistance in designing and fabricating what is known as an opto-electro-mechanical micro-converter—a combination of a micro-electromechanical and an optical sensor, which makes it possible to detect radio signals with a laser beam.

An integrated chip
The researchers have now proved the feasibility of the concept, but the technology needs to be developed further before it can enter production.

“Our next challenge is to adapt the converter to make it possible to work at higher frequencies (microwaves), and to create a converter as a tiny integrated chip which, in the future, can be embedded e.g. in an MRI scanner or a mobile phone,” says Associate Professor Silvan Schmid.

An eardrum for electronic signals
He compares the technology to the human ear, where acoustic waves make the ear drums vibrate. A similar process takes place in the new converter, where radio waves rather than acoustic waves trigger a mechanical response in a micromembrane.

The technology comprises a thin membrane of silicon nitride, which is covered with a mirror-like layer of aluminium. The micromembrane is suspended above an electrode, forming a condenser that is part of an antenna, which captures radio waves within its resonance frequency.

The membrane is just half a millimetre wide and one hundred nanometres thick. Electric charges induced by radio waves pass through the electrodes which makes the membrane vibrate. A laser light reflected off the membrane then converts the faint radio waves into an optical signal.

Read the article in Nature

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