8-16 News v2 10/9/09 13:24 Page 14
news review
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Tiny rays of hope
The University of California has reported a region stores light within an area 20 times
new milestone in laser physics by creating smaller than its wavelength. Because light
the world’s smallest semiconductor laser, energy is largely stored in this tiny non-
capable of generating visible light in a space metallic gap, loss is significantly diminished.
smaller than a single protein molecule. This
breakthrough, described in an advanced With the loss finally under control through
online publication of the journal Nature this unique “hybrid” design, the researchers
breaks new ground in the field of optics. could then work on amplifying the light.
The UC Berkeley team successfully “When you are working at such small
squeezed light into such a tight space and scales, you do not have much space to play
found a novel way to keep that light energy around with,” said Rupert Oulton, the
from dissipating as it moved along, thereby research associate in who first theorized this
achieving laser action. “This work shatters approach and the study’s co-lead author. “In said Volker Sorger, a Ph.D. student and
traditional notions of laser limits, and makes our design, the nanowire acts as both a study co-lead author.“Plasmon lasers
a major advance toward applications in the confinement mechanism and an amplifier. represent an exciting class of coherent light
biomedical, communications and computing It’s pulling double duty.” The UC Berkeley sources capable of extremely small
fields,” said Xiang Zhang, director at UC researchers used semiconductor materials confinement,” said Zhang. “This work can
Berkeley of a National Science Foundation and fabrication technologies that are bridge the worlds of electronics and optics
(NSF) Nanoscale Science and Engineering commonly employed in modern electronics at truly molecular length scales.”
Center. manufacturing. By engineering hybrid
surface plasmons in the tiny gap between Scientists hope to shrink light down to the
The achievement helps enable the semiconductors and metals, they were able size of an electron’s wavelength, which is
development of such innovations as to sustain the strongly confined light long about a nanometer, or one-billionth of a
nanolasers that can probe, manipulate and enough that its oscillations stabilized into meter, so that the two can work together on
characterize DNA molecules; optics-based the coherent state that is a key equal footing. In addition to the three co-
telecommunications many times faster than characteristic of a laser. lead authors, other co-authors of the paper
current technology; and optical computing are Renmin Ma and Lun Dai from Peking
in which light replaces electronic circuitry “What is particularly exciting about the University, and Christopher Gladden and
with a corresponding leap in speed and plasmonic lasers is that they are solid state Guy Bartal from Zhang’s research group.
processing power. While it is traditionally and fully compatible with semiconductor
accepted that an electromagnetic wave - manufacturing, so they can be electrically This work is supported by the U.S. Air Force
including laser light - cannot be focused pumped and fully integrated at chip-scale,” Office of Scientific Research and the NSF.
beyond the size of half its wavelength,
research teams around the world have
found a way to compress light down to
dozens of nanometers by binding it to the
Dicing greater yield
electrons that oscillate collectively at the
surface of metals. This interaction between Veeco Instruments has announced
light and oscillating electrons is known as the introduction of its Optium ADS-800TM
surface plasmons. Series Advanced Dicing System,
delivering dicing solutions for a broad
Scientists have been racing to construct range of applications, including high
surface plasmon lasers that can sustain and brightness light emitting diodes (HB-
utilize these tiny optical excitations. LEDs), solar cells, optics, and
However, the resistance inherent in metals microelectronics.
causes these surface plasmons to dissipate
almost immediately after being generated, Robert P. Oates, Executive Vice President,
posing a critical challenge to achieving the commented, “Our new ADS-800 Series
buildup of the electromagnetic field Advanced Dicing System incorporates
necessary for lasing. over 30 years of dicing expertise, offering
high throughput and precise cutting of
Zhang, a professor of mechanical premium devices, critical for emerging
engineering, and his team took a novel markets such as LED and solar.
approach to stem the loss of light energy by multi-blade cutting technology.”
pairing a cadmium sulfide nanowire - 1,000 We are able to reduce manufacturers’ The Optium ADS-800 Series has
times thinner than a human hair - with a dicing saw capital costs by over 40% due been designed for R&D environments,
silver surface separated by an insulating gap to our tool’s highly rigid cast iron structure, pilot line production and high volume
of only 5 nanometers, the size of a single high performance air bearing spindle and production.
protein molecule. In this structure, the gap
14 www.compoundsemiconductor.net September 2009
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