New nitride phosphor from Philips Lumileds closes yellow LED gap
Researchers with Philips Lumileds (San Jose, CA) have developed a monochromatic nitride diode that closes the yellow light-emitting diode (LED) gap. The phosphor-converted (PC) amber LED demonstrated by Regina Mueller-Mach and her colleagues uses the down-conversion of blue light from an indium-gallium-nitride (InGaN) LED to longer-wavelength light by a phosphor, in a variation of a well-established process for producing cold or warm white light from blue LED light (see also "Fluorescent microspheres create white-light LEDs").
Monochromatic light-emitting diodes cover a large part of the visible spectrum with high efficiency. For blue light, nitride diodes achieve external quantum efficiencies in excess of 65%. For red light, phosphor diodes achieve efficiencies of approximately 50%. However, so far no highly efficient monochromatic LEDs have been available for the "yellow gap" at around 560 nm.
Leveraging previous research on warm white light, the researchers succeeded in down-converting blue LED light into monochromatic amber light with a 595 nm wavelength and a color purity of 98.7%. The external quantum efficiency of the PC amber LED is at 30-40%, depending on temperature. Compared to direct amber LEDs, the new PC amber LED is two to five times as bright. It achieves a light output of 70 lumens at a 350 mA current.
There are numerous applications for the LUXEON Rebel PC Amber LED. It can be used in yellow traffic lights or signals as well as in cars' turn signals or warning lights for construction sites. They could also be used in consumer electronics and their high efficiency makes them inexpensive.
For more information, go to www.philipslumileds.com.
Gail Overton | Senior Editor (2004-2020)
Gail has more than 30 years of engineering, marketing, product management, and editorial experience in the photonics and optical communications industry. Before joining the staff at Laser Focus World in 2004, she held many product management and product marketing roles in the fiber-optics industry, most notably at Hughes (El Segundo, CA), GTE Labs (Waltham, MA), Corning (Corning, NY), Photon Kinetics (Beaverton, OR), and Newport Corporation (Irvine, CA). During her marketing career, Gail published articles in WDM Solutions and Sensors magazine and traveled internationally to conduct product and sales training. Gail received her BS degree in physics, with an emphasis in optics, from San Diego State University in San Diego, CA in May 1986.