Lasers used to convert radio waves to light signals

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A group of researchers from The Niels Bohr Institute has outlined a successful attempt to convert radio signals into optical pulses that can be transmitted over optic cables using lasers. The work was outlined in a letter to the journal Nature.

The researchers believe it could lead to reduced noise and better quality MRI scans, and will hugely benefit stellar observations, as the technique can detect very weak radio signals.

The technique uses an antenna to detect radio waves and passes the signal onto a capacitor containing an aluminium coated silicon nitride nanomembrane. This layer fluctuates in the presence of an electric field from the radio wave signal.

A laser is then directed at the sheet and by measuring a change in the beam’s light waves, the fluctuations can be recorded and transmitted along a fibre optic cable.

The device also doesn’t need to be cooled to reduce noise meaning it can operate at room temperature. By confining the nanomembrane within a vacuum it behaves as if it was at 2°K (-271°C); this drastically reduces noise from thermal excitement of the atoms and electrons. Also by using a laser to measure the fluctuations, all of the photons are identical, and the team say this means there is virtually no quantum noise.

The reduced noise at convenient temperatures makes this device very sensitive, even to the weakest of radio waves. This opens the technology up to new research and could further space science, medical imaging, and could allow for communication between quantum and conventional computers.