on the Frontiers
New devices manipulate light in unusual ways that
Existing computer chips such
as these run on electricity,
but the next generation will
run on photons.
can enable ultrasensitive detection, leading to
applications such as quantum communication
and quantum computing.
Computer chips based on light as op- posed to electricity have only been theorized, but now researchers are
actually developing computer chips that
will use light for computer functions.
At Yale University in New Haven,
Conn., members of Hong Tang’s lab are
already taking development of these photonic computer chips a step further. They
are using light to power nanomachines
built from computer chips, and these
nanomachines could have numerous applications, including sensing molecules and
even smaller particles.
The photonic nanomachines are similar
to micro- and nanomachines that are powered by electricity, which are formally
called micro- and nanoelectromechanical
systems, or MEMS and NEMS, respectively. Far from a lab curiosity, MEMS devices have been deployed in automobile air-bag sensors, ink-jet printers and even the
motion sensors in Nintendo Wii controllers.
The researchers in the Tang lab have
BY DAVID L. SHENKENBERG
found an optical force that behaves like the
Casimir force found in tiny electrical machines. This force is usually weak but becomes significant in micro- and nanode-vices. The photonic chip will enable them
to study this weak force, as well as to develop applications.
This force is different from the radiation
pressure that is used by optical tweezers to
move particles. “The new force that we
have investigated actually kicks to the side
of that light flow,” Tang said.
Enter the matrix
The researchers have used the optical
force to move 10 tiny cantilevers on a
CMOS chip. Tang said, “The significance
of our CMOS platform is that our device is
fully compatible with many other devices.
You can cascade them, put them in parallel,
multiplex, scale up the production.”
As described in the April 26, 2009,
issue of Nature Nanotechnology, the light
goes through the hollow bore of each
nanocantilever and is collected on-chip.
The nanocantilevers are of different
lengths and therefore resonate at different
frequencies, like keys on a xylophone. The
system can detect particles 1⁄
10,000 the size
of an atom, or 0.0001 angstroms. The detection mechanism is based on the deflection of the cantilevers.
The system can operate with inexpensive LEDs as opposed to more expensive
laser systems, and at room temperature as
opposed to extreme cold – major advantages over detectors with comparable sensitivity, according to the researchers.
In the July 13, 2009, issue of Nature
Photonics, they reported that the optical
force can be repulsive as well as attractive,
a feature that could be used as a routing
mechanism for communication between
devices that contain computer chips.
In particular, this device possibly could
be used as a router for quantum communication, which promises faster and more
efficient communication between devices