The new laser breakthrough may one day usher in a new era in
computing power by providing CPU makers with the ability to use light
rather than electronic circuitry in processors. The key breakthrough
was a method that the researchers devised to squeeze
the light into a space smaller than its wavelength and keep the
light from dissipating as it moved along.
shatters traditional notions of laser limits, and makes a major
advance toward applications in the biomedical, communications and
computing fields," said Xiang Zhang, professor of mechanical
engineering and director of UC Berkeley's Nanoscale Science and
Engineering Center, which is funded by the National Science
Foundation (NSF), and head of the research team behind this
The scientists say that the breakthrough will help usher
in innovations like nanolasers that can probe and manipulate DNA
molecules, optics based telecommunications and optical computing.
Traditionally it is accepted that light can be compressed into a
space smaller than half the size of its wavelength. Researchers have
been able to compress light down to a couple nanometers by binding it
to electrons that oscillate collectively along the surface of metals,
otherwise known as plasmons.
Zhang and his team improved on
this technique by pairing a cadmium sulfide nanowire with a silver
surface separated by an insulating gap only 5nm wide or about the
size of a protein molecule. The structure is able to store the light
within an area 20 times smaller than the wavelength of the light. The
light energy is reportedly stored mostly in the insulating gap
between the wire and the silver surface loss is diminished
"When you are working at such small
scales, you do not have much space to play around with," said
Rupert Oulton, the research associate in Zhang's lab who first
theorized this approach last year and the study's co-lead author. "In
our design, the nanowire acts as both a confinement mechanism and an
amplifier. It's pulling double duty."
sustaining light in the very tight quarters creates conditions where
the interaction of light and matter is strongly altered. The
researchers say the sign of this altered interaction is a six-fold
increase in the emission rate of light in the 5nm gap.
is particularly exciting about the plasmonic lasers we demonstrated
here is that they are solid state and fully compatible with
semiconductor manufacturing, so they can be electrically pumped and
fully integrated at chip-scale," said Volker Sorger, a Ph.D.
student in Zhang's lab and study co-lead author.