In a decade, some scientists expect there to be no buzzing from
loud fans in laptops and say MP3 players will ideally run at least
100 times faster because electronic chips will be dominated by
silicon optical amplifiers, an advancement based on the discoveries
in engineering announced two weeks ago.
A group of researchers at the UCLA Henry Samueli School of
Engineering and Applied Science announced on June 28 a breakthrough
in the development of silicon photonics. Scientists hope that by
using silicon in short-distance communication, information can be
transferred with great speed and no energy cost.
After scientists in the UCLA engineering department demonstrated
the first use of the silicon laser in 2004 and Intel contributed by
allowing the use of continuous light, a team headed by electrical
engineering Professor Bahram Jalali started a project to research
silicon chips.
With silicon becoming increasingly important in electronics, the
goal of the project was to combine silicon and optics, or light,
for chip-to-chip communication.
“Silicon is the wonder material of modern times,”
Jalali said.
By replacing the copper wires that are currently being used to
connect chips with silicon, optics can address the common problem
of speed because light is being used, said Kevin Tsia, a graduate
student in the School of Engineering who is participating in the
research.
“We’re always trying to shrink the size and increase
the speed of electronic devices,” Tsia said. “But the
bottom line is that copper wires cannot accommodate such speed.
Optics can.”
The main problem with using silicon, however, is that it becomes
opaque at high optical intensities due to the process of light
absorption called two-photon absorption, causing additional loss of
energy, Jalali said.
Postdoctorate fellow Sasan Fathpour and Tsia found a way to
overcome that problem through silicon’s light-harvesting
characteristic known as the Raman effect.
“We had to think outside of the box to see that the
photovoltaic property could be applied in a way similar to that of
solar cells using sunlight to harvest energy,” Fathpour
said.
Not only would no energy be required, compared to the 1 watt of
input energy that would be needed to amplify light without using
the Raman effect, but a few milliwatts of power can even be
generated, Jalali said.
“This development is a major stepping stone because power
dissipation is the No. 1 problem right now,” Jalali said.
The three greatest areas of direct impact will be in chip
communication, optical sensors and high-power lasers used for
defense, Jalali said.
Now that the use of silicon in photonics to generate energy has
been discovered, the next step will be to reduce the size of the
chips that use silicon from centimeters to microns so they can fit
in devices, Jalali said. Currently, silicon chips can be made, but
are still too big to use.
“We’ve made significant progress but it won’t
be another three to five years until silicon photonics will be
available in industry,” Jalali said.