Infrared and visible light LEDs and photodetectors have found numerous applications and have become a truly enabling technology. The promise of solid state lighting has invigorated interest in white light LEDs. Ultraviolet LEDs and solar blind photodetectors represent the next frontier in solid state emitters and hold promise for many important applications in biology, medi­ cine, dentistry, solid state lighting, displays, dense data storage, and semi­ conductor manufacturing. One of the most important applications is in sys­ tems for the identification of hazardous biological agents. Compared to UV lamps, UV LEDs have lower power consumption, a longer life, compactness, and sharper spectral lines. UV LEDs can provide a variety of UV spectra and have shape and form factor flexibility and rugged­ ness. Using conventional phosphors, UV LEDs can generate white light with high CRI and high efficiency. If quantum cutter phosphors are developed, white light generation by UV LEDs might become even more efficient. Advances in semiconductor materials and in improved light extraction techniques led to the development of a new generation of efficient and pow­ erful visible high-brightness LEDs and we expect that similar improvements will be achieved in solid-state UV technology.