|Artist's impression of nanophotonics. Courtesy: NanoPhotonics Cambridge/Bart deNijs.|
Researchers in the UK and Spain have succeeded in confining light to a volume smaller than the size of a single atom for the first time – a feat that seemed completely impossible even just a few years ago. The “picocavity”, which can be thought of as the world’s smallest magnifying glass, could be used to study how light and matter interact at tiny scales and even to observe individual chemical bonds forming and breaking between atoms. The cavity might also be used to make new optomechanical data storage devices in which information can be written and read by light and stored in the form of molecular vibrations.
For a long time, scientists thought that visible light could not be focused to less than half its wavelength – the so-called diffraction limit. In recent years, however, they have learnt how to use nanostructured metals like gold and silver that support surface plasmons (oscillations of electrons at the metal surface) to confine optical fields to much smaller than their wavelength.
Now, a team led by Jeremy Baumberg at Cambridge University in the UK has used highly conductive gold nanoparticles to make the world’s tiniest optical cavity. This cavity is so small that only a single atom can fit in it. “We will never do any better than this!” says Baumberg.
Nanotechweb: Picocavity confines light to smallest volume ever, Belle Dumé