Abstract

White light-emitting diodes (LED) became a commercial reality almost three decades after the demonstration of the first monochromatic LED. The LED’s potential for energy savings and the promise of reduced maintenance costs are the two main features that caught the attention of the community interested in general illumination. So far, LEDs have proved their usefulness and have started to displace traditional light sources, such as the incandescent lamp, in certain niche applications where monochromatic light is required. However, LEDs have yet to demonstrate their capabilities in general lighting applications. At present, researchers and manufacturers around the world are aggressively working toward developing a light source that could replace traditional light sources, such as incandescent and fluorescent lamps, in general lighting applications. For LEDs to directly compete with any of these technologies for a given application, they have to meet the characteristics of the target light sources in all areas. As an example, although amber LEDs have demonstrated luminous efficacies greater than 100 lm/W, they cannot compete with fluorescent lamps in office lighting applications because luminous efficacy is not the only parameter that makes a fluorescent lamp suitable for this application.

© 2004 Optical Society of America