Tiny silicon bowtie structure claims record photon confinement in time and space.

A newly designed photonic crystal traps light using a series of bow-tie-shaped gaps. Photon density (depicted in 3D for easy visualization) is highest at the centre of the bow tie’s knot (red) and dwindles (from yellow to green to purple) towards the knot’s outer edges. Credit: Ella Maru Studio

Optics and photonics

‘Bow ties’ break record for bottling up light

Similar designs could store information in circuits that carry light instead of electrical current.

Light can be trapped with unprecedented effectiveness inside a device smaller than a dust particle.

The device is a photonic crystal, a structure that can transmit specific wavelengths of light while blocking others. Such structures can be fashioned to include minuscule cavities, called resonators, that trap light. Future photonic circuits — which would carry light instead of electric current — could rely on resonators to store bits of information in the form of light pulses.

Sharon Weiss at Vanderbilt University in Nashville, Tennessee, and her collaborators carved a slab of silicon with bow-tie-shaped openings: two roughly triangular gaps connected by a 12-nanometre-wide silicon bridge. Together, the shapes trap light close to the ‘knots’ of the bow ties, concentrating photons at densities at least 60 times higher than achieved with previous photonic crystals.

Structures that concentrate light in this way could be useful for making efficient photonic transistors, which allow the passage of light through circuits to be switched on or off.