|[March 03, 2014]
Novel Quantum Dot Laser Paves the Way for Lower-cost Photonics
WASHINGTON --(Business Wire)--
With the explosive growth of bandwidth demand in telecommunications
networks, experts are continually seeking new ways to transmit
increasingly large amounts of data in the quickest and cheapest ways
possible. Photonic devices-which convert light to electricity and vice
versa-offer an energy-efficient alternative to traditional copper
network links for information transmission. Unfortunately, these devices
are also almost always prohibitively pricey.
One way to bring those costs down is to make photonics compatible with
the existing silicon microelectronics industry. A promising way to do
that is by growing "quantum dot" lasers directly on silicon substrates,
according to graduate student Alan Y. Liu of the University of
California at Santa Barbara (UCSB) and his colleagues, who include UCSB
professors John E. Bowers and Arthur C. Gossard. Although such quantum
dot lasers have been grown on silicon before, their performance has
not�equaled�that of quantum dot lasers grown on their native substrates,
which are�platforms made of�similar�materials as the quantum dot
Now Liu and his collaborators in Bowers and Gossard's groups have
demonstrated a novel quantum dot laser that not only is grown on silicon
but that performs as well as similar lasers grown on their native
substrates. The team will discuss its record-breaking results achieved
using such lasers at this year's OFC
Conference and Exposition, being held�March 9-13 in San Francisco,
The researchers believe the work is an important step towards
large-scale photonic integration in an ultra low-cost platform.
Currently, so-called "quantum well" lasers are used for data
transmission. They consist of nanometers-thic layers of light-emitting
material, representing the quantum well, sandwiched between other
materials that serve to guide both the injected electrical current as
well as the output light. A quantum dot laser is similar in design, but
the sheets of quantum well materials are replaced with a high density of
smaller dots, each a few nanometers high and tens of nanometers across.
To put it in perspective, 50 billion of them would fit onto one side of
"Quantum (News - Alert) wells are continuous in two dimensions, so imperfections in one
part of the well can affect the entire layer. Quantum dots, however, are
independent of each other, and as such they are less sensitive to the
crystal imperfections resulting from the growth of laser material on
silicon," Liu said.
"Because of this, we can grow these lasers on larger and cheaper silicon
substrates. And because of their small size," Liu added, "they require
less power to operate than quantum well lasers while outputting more
light, so they would enable low-cost silicon photonics."
In their new work, the team grew quantum dots directly on silicon
substrates using a technique known as molecular beam epitaxy, or MBE
("epitaxy" refers to the process of growing one crystal on top of
another, with the orientation of the top layer determined by that of the
"The major advantage of epitaxial growth is that it enables us to
exploit the existing economies of scale for silicon, which would drive
down cost," Liu said. He added that "MBE is the best method for creating
high-quality quantum dots that are suitable for use in lasers" and that
"the entire laser can be grown continuously in a single run, which
minimizes potential contamination."
Presentation W4C.5. titled "High Performance 1.3�m InAs Quantum Dot
Lasers Epitaxially Grown on Silicon" will take place Wednesday, March 12
at 5:00 p.m. in room 121 of the Moscone Center.
PRESS REGISTRATION: A press room for credentialed press and analysts
will be located in the Moscone Center, Sunday through Thursday, March
9-13. Those interested in obtaining a press badge for OFC should contact firstname.lastname@example.org.
EDITOR'S NOTE: High-resolution images are available upon request.
Contact Lyndsay Meyer, email@example.com.
Note: This work was recently published in Applied Physics Letters:
Liu, A. Y., et al. "High performance continuous wave 1.3 �m quantum dot
lasers on silicon." Applied Physics Letters, 104, 041104 (2014)
For more than 35 years, OFC has been the premier destination for
converging breakthrough research and innovation in telecommunications,
optical networking, fiber optics and, recently, datacom and computing.
Consistently ranked in the top 200 tradeshows in the United States, and
named one of the Fastest Growing Trade Shows in 2012 by TSNN, the
conference unites service providers, systems companies, enterprise
customers, IT businesses, and component manufacturers, with researchers,
engineers, and development teams from around the world. OFC includes
dynamic business programming, an exposition of more than 550 companies,
and cutting-edge peer-reviewed research that, combined, showcase the
trends and pulse of the entire optical networking and communications
industry. OFC is managed by The Optical Society (OSA) and co-sponsored
by OSA, the IEEE (News - Alert) Communications Society (IEEE/ComSoc), and the IEEE
Photonics Society. OFC 2014 takes place March 9-13 at the Moscone
Convention Center in San Francisco, Calif., USA.
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