The Photon Recycling Semiconductor Light-Emitting Diode
(PRS-LED) developed by Fred Schubert, a professor of electrical and computer
engineering at Boston University's Photonics Center, is said to be 15 to 20
times more efficient than conventional light bulbs. The PRS-FED may some day
replace incandescent, fluorescent, and sodium vapor lights in many applications
because it efficiently generates up to 300 lumens per watt. An LED generates
light through an electronic process. Electrons enter a light-emitting active
region through external wires where the electrical energy of the electrons is
transformed into light particles or photons. Unlike other LEDs that have one
active region and produce a single color of light, Schubert's PRS-LED uses at
least two active regions. The first region converts electrons into photons in
the blue range. Some of the photons are directed to the second region which
absorbs the light then re-emits it at a different wavelength that produces
photons in the yellow-orange-red range. Changing the active regions produces
different wavelengths that are configured for producing hundreds of colors,
including white light commonly used in homes and public spaces. Schubert
indicates that additional potential applications for the PRS-LEDs include signs
and displays for automotive dashboards. He also indicated that, although Boston
University's primary goal is the education of students, the university is
interested in commercialization. "Sure, we are always interested in escaping
from the confines of our ivory tower and working with companies," he says.
Contact Schubert at (617) 353-1910, fax (617) 353-6440, or e-mail him at email@example.com .
Reducing the cost of fiber optics
Peter Esherick is making progress in the task of
reducing the high cost of fiber-optic connections. As the manager of the
Compound Semiconductor Materials and Processes Department at Sandia National
Labs (Albuquerque, NM), he is developing the first 1.3-micron electrically
pumped laser that promises to meet the high-speed communications needs fueled by
the growing demand for faster Internet access. The vertical cavity
surface-emitting laser (VCSEL) that Esherick developed is made mostly from
layers of aluminum gallium arsenide and gallium arsenide. An additional
ingredient, indium gallium arsenide nitride, causes the VCSEL's operating
wavelength to fall into a range that makes it useable in high-speed Internet
connections. "We are working with Cielo Communications Inc. (Bloomfield, CO) in
a cooperative research and development agreement and they are aggressively
pursuing commercialization in telecommunications applications," says Esherick.
"However, there may be other applications beyond telecommunications. For
example, we are looking at the integration of this technology with microsystems
machined from silicon for national security systems," he says. The laser
provides a light source that transmits information down optical fibers. In the
VCSEL, laser photons bounce between mirrors and are vertically emitted from the
wafer surface. "The VCSELs, which are grown by the thousands on a single wafer,
are certainly easier to produce than the edge emitter lasers that are currently
used," says Esherick. "We expect there to be a great deal of excitement over
this product," he says. Contact Esherick at (505) 844-5857 or visit the Sandia
National Lab website at www.sandia.gov .
Improving OLED efficiency
Stephen Forrest and collaborators from Princeton
University have developed a new cold-welding process for patterning electrodes
in OLEDs (Organic LEDs). "A real issue with OLEDs is the ability to pattern
quickly without wet chemicals," says Forrest. He believes the new patent-pending
process will reduce display-manufacturing costs and make the displays operate
with greater efficiency than displays manufactured with other processing
techniques. "It only takes us about three minutes to make a display pattern for
a cathode," he says. The new process involves pressing a pre-patterned
metal-coated stamp onto an unpatterned layer that forms the metal cathode layer
of the OLED. Forrest says the process is a little like pulling lint from
clothing using a piece of tape. The metal pattern cold-welds to the metal
cathode that coats the underlay organic films when pressure is applied to the
metal pattern. The next step in the process involves lifting off the cold-welded
cathode material from the device, which results in submicrometer feature
definition. Contact Forrest at firstname.lastname@example.org .
The engineers and inventors of the post WWII period turned their attention to advancements in electronics, communication, and entertainment. Breakthrough inventions range from LEGOs and computer gaming to the integrated circuit and Ethernet -- a range of advancements that have little in common except they changed our lives.
Neil Fromer is the executive director of the Resnick Institute, a program for energy and sustainability at the California Institute of Technology, working to develop new ideas and research technologies related to providing a sustainable future. He spoke to us about the severity of the current drought in California and how solar energy can help prevent such situations in the future.
From home enthusiasts to workers on the manufacturing floor, everyone's imagination is captured by the potential of 3D printing. Prototyping, spare parts creation, art delivery, human organ creation, and even mass product production are all being targeted as current and potential uses for the technology.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.