Computer chips based on light as op- posed to electricity have only been theorized, but now researchers areactually developing computer chips thatwill use light for computer functions.
At Yale University in New Haven,Conn., members of Hong Tang’s lab arealready taking development of these photonic computer chips a step further. Theyare using light to power nanomachinesbuilt from computer chips, and thesenanomachines could have numerous applications, including sensing molecules andeven smaller particles.
The photonic nanomachines are similarto micro- and nanomachines that are powered by electricity, which are formallycalled micro- and nanoelectromechanicalsystems, 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 themotion sensors in Nintendo Wii controllers.
The researchers in the Tang lab have
found an optical force that behaves like the
Casimir force found in tiny electrical ma-
chines. This force is usually weak but be-
comes significant in micro- and nanode-
vices. The photonic chip will enable them
to study this weak force, as well as to de-
This force is different from the radiationpressure that is used by optical tweezers tomove particles. “The new force that wehave investigated actually kicks to the sideof 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,
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 de-
tection mechanism is based on the deflec-
tion of the cantilevers.
The system can operate with inexpensive LEDs as opposed to more expensivelaser systems, and at room temperature asopposed to extreme cold – major advantages over detectors with comparable sensitivity, according to the researchers.
In the July 13, 2009, issue of NaturePhotonics, they reported that the opticalforce can be repulsive as well as attractive,a feature that could be used as a routingmechanism for communication betweendevices that contain computer chips.
In particular, this device possibly couldbe used as a router for quantum communication, which promises faster and moreefficient communication between devices
Existing computer chips suchas these run on electricity,but the next generation willrun on photons.
on the Frontiers
New devices manipulate light in unusual ways thatcan enable ultrasensitive detection, leading toapplications such as quantum communicationand quantum computing.
BY DAVID L. SHENKENBERGFEATURES EDITOR