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Green UV Sterilization: Switching on LEDs to Save Energy and the Environment

02.05.2011
Ultraviolet light can safely sterilize food, water and medical equipment by disrupting the DNA and other reproductive molecules in harmful bacteria.

Traditionally, mercury lamps have supplied this UV light, however mercury release from power generation and lamp disposal have generated discussion of harmful environmental impact. A potentially energy efficient and non-toxic alternative is the light-emitting diode, or LED, which can be made to emit at almost any desired wavelength.

LEDs are also more rugged and operate at lower voltages than glass containing mercury bulbs. Thus, LEDs are more compatible with portable water disinfection units, which could also be solar-powered and used in situations where centralized facilities are not available, such as disaster relief. LEDs currently require a lot of electricity to produce UV light, but researchers from around the world are focused on improving this efficiency.

LEDs are semiconductor devices that operate in much the same way as the tiny elements on a computer chip. The difference is that some of the electrons flowing into an LED are captured and release their energy as light. Because these are solid materials rather than gas-filled bulbs, LEDs are more compact and durable than alternative light sources. The first commercial LEDs were small red indicator lights, but engineers have developed new materials that emit in a rainbow of colors. Nitride-based LEDs are the most promising for pushing beyond the visible into the ultraviolet. Some of these UV LEDs are already being used in the curing of ink and the testing for counterfeit money, but for sterilization, shorter wavelength light is required. These short wavelength, or “Deep UV” LEDs, present a number of technical challenges and are predominantly implemented in highly specialized disinfection systems in industrial and medical applications, as well as other non-disinfection markets.

The Joint Symposium on Semiconductor Ultraviolet LEDs and Lasers (CLEO: 2011, May 1-6 in Baltimore) will feature several talks addressing these challenges, while highlighting current efforts to improve the efficiency of nitride-based LEDs. Max Shatalov of Sensor Electronic Technology in Columbia, S.C., will report an improved design for making high-power UV LEDs that would be especially good for knocking out bacteria. From the birthplace of nitride (blue and white) LEDs, Motoaki Iwaya from Meijo University in Japan will describe a joint effort with Nagoya University to extend the range and improve the efficiency of UV LEDs.

The application of these UV LEDs is also being pursued in a related CLEO: 2011 session. Gordon Knight from Trojan Technologies in Canada will review advances in production of novel UV light sources, along with necessary validation procedures for verifying the operation of water disinfection systems in a one-hour tutorial.

Presentation JTuD1, “High Power III-Nitride UV Emitters,” by Max Shatalov et al. is at 11 a.m. Tuesday, May 3.

Presentation JTuD2, “IQE and EQE of the nitride-based UV/DUV LEDs,” by Motoaki Iwaya et al. is at 11:30 a.m. Tuesday, May 3.

Tutorial ATuD1, “Water and Air Treatment Using Ultraviolet Light Sources,” by Gordon Knight is at 1:45 p.m. Tuesday, May 3.

CLEO: 2011 Program Information
CLEO: 2011 unites the fields of lasers and optoelectronics by bringing together all aspects of laser technology, from basic research to industry applications. The main broad topics areas at the meeting are fundamental science, science and innovations, applications and technology, and market focus. An exposition featuring 300 participating companies will be held concurrently with the scientific presentations.

Plenary Session keynote speakers include Donald Keck, retired vice president of Corning, talking about making the first low-loss optical fibers; James Fujimoto of MIT, talking about medical imaging using optical coherence tomography (OCT); Mordechai (Moti) Segev of the Technion-Israel Institute of Technology, speaking about the localization of light; and Susumu Noda of Kyoto University, talking about the control of photons in photonic crystals.

Online resources:

• Conference program: http://www.cleoconference.org/Conference_Program
• CLEO: Expo: http://www.cleoconference.org/exhibit_hall
• Press Center: http://www.cleoconference.org/media_center
• Plenary Session: http://www.cleoconference.org/Conference_Program
• Special Symposia: http://www.cleoconference.org/Conference_Program/symposia.aspx

• Conference Registration: http://www.cleoconference.org/registration

Press Registration
A Press Room for credentialed press and analysts will be located on-site in the Baltimore Convention Center, Sunday, May 1 – Thursday, May 5. Media interested in attending the conference should register online at http://www.cleoconference.org/media_center/mediaregistrationform.aspx or contact Angela Stark at 202.416.1443, astark@osa.org.
About CLEO
With a distinguished history as the industry's leading event on laser science, the Conference on Lasers and Electro-Optics (CLEO) and the Quantum Electronics Laser Science Conference (QELS) is where laser technology was first introduced. CLEO: 2011 will unite the field of lasers and electro-optics by bringing together all aspects of laser technology, with content stemming from basic research to industry application. Sponsored by the American Physical Society's (APS) Laser Science Division, the Institute of Electronic Engineers (IEEE) Photonics Society and the Optical Society (OSA), CLEO: 2011 provides the full range of critical developments in the field, showcasing the most significant milestones from laboratory to marketplace. With an unparalleled breadth and depth of coverage, CLEO: 2011 connects all of the critical vertical markets in lasers and electro-optics. For more information, visit the conference's website at www.cleoconference.org.

Angela Stark | Newswise Science News
Further information:
http://www.osa.org

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