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White Light-emitting Diode (white + light-emitting_diode)
Selected AbstractsRecent Progress in GaN-Based Light-Emitting DiodesADVANCED MATERIALS, Issue 45 2009Haiqiang Jia Abstract In the last few years the GaN-based white light-emitting diode (LED) has been remarkable as a commercially available solid-state light source. To increase the luminescence power, we studied GaN LED epitaxial materials. First, a special maskless V-grooved c -plane sapphire was fabricated, a GaN lateral epitaxial overgrowth method on this substrate was developed, and consequently GaN films are obtained with low dislocation densities and an increased light-emitting efficiency (because of the enhanced reflection from the V-grooved plane). Furthermore, anomalous tunneling-assisted carrier transfer in an asymmetrically coupled InGaN/GaN quantum well structure was studied. A new quantum well structure using this effect is designed to enhance the luminescent efficiency of the LED to ,72%. Finally, a single-chip phosphor-free white LED is fabricated, a stable white light is emitted for currents from 20 to 60,mA, which makes the LED chip suitable for lighting applications. [source] Visible light wireless transmission based on optical access network using white light-emitting diode and electroabsorption transceiverMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2010Yong-Hwan Son Abstract We propose the visible light communication (VLC) system based on optical access network using light-emitting diode (LED) and electroabsorption transceiver (EAT). The EAT based on electroabsorption modulator is used as an optical network unit in order to be connected with VLC link based on white LED and photodiode (PD). The proposed architecture is demonstrated experimentally, and its performance is verified through the experimental investigation of quality factor and eye pattern of 5 Mbps baseband data. The variation of performance is shown depending on both the existence of the ambient light and the distance between the LED array and PD. A total of 5 Mbps downlink and uplink transmission is verified through 23.2-km single-mode fiber and wireless channel experimentally. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:790,793, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25045 [source] Present Status of Energy Saving Technologies and Future Prospect in White LED LightingIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 1 2008Tsunemasa Taguchi Member Abstract This paper describes the present status and future prospects on the efficient energy-saving lighting system based on white light-emitting diodes (LEDs) technologies. Three types of white LEDs are introduced in terms of the fundamental lighting properties which are related to the improvement in luminous efficacy and color rendering. Practical applications using the efficient white LED lighting system are demonstrated. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Synthesis and Luminescence Properties of Orange,Red-Emitting M2Si5N8:Eu2+ (M=Ca, Sr, Ba) Light-Emitting Diode Conversion Phosphors by a Simple Nitridation of MSi2INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2009Hui-Li Li Eu2+ -doped M2Si5N8 (M=Ca, Sr, Ba) orange,red phosphors were successfully prepared by a simple, direct, and efficient solid-state reaction using air-stable MSi2, Eu2O3, and ,-Si3N4 as the starting materials under N2,H2 (5%) atmosphere. The influence of the type of the alkaline-earth ion on the phase structure and luminescence properties has been investigated. The results show that the synthesized powders have a single-phase crystal structure of M2Si5N8 for M=Ca, Sr, and a little amount of BaSi7N10 impurity phase for M=Ba. Under the blue light excitation, M2Si5N8:Eu2+ shows a typical broad band emission of Eu2+ ranging from orange to red (585,620 nm) depending on the type of M ion. The emission intensity, conversion efficiency, and thermal stability increase with the sequence of Ca
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