March 2001

New Light

By Technology Review

Incandescent bulbs offer warm, but inefficient, illumination. Fluorescent lights save energy and last longer but cast a greenish glow. With the help of researchers at Brown University, engineers at Sandia National Laboratories in Albuquerque, NM, have come up with a brighter idea. They've developed a tiny solid-state laser that promises to deliver a longer-lasting white light while using minimal electricity. Related to the LEDs that blink in electronic appliances, the device emits ultraviolet light, which strikes a phosphor coating; the phosphor glows with an eye-pleasing white light. Lightbulbs made from the chips could last up to 10 times longer than fluorescent bulbs and up to 50 times longer than incandescent ones. The invention, only 20 micrometers square, requires the help of large conventional lasers; an electrically powered prototype should be ready within two years, with commercial models due in five to 10 years.