Developments to Watch
NOW, LEDs MAY GIVE LASERS A RUN FOR THE MONEY
Light-emitting diodes are the poor cousins of lasers. Although cheaper and more reliable than lasers, they're not as bright and can't turn on and off as rapidly. That's why lasers are the light sources of choice for fiber optics, laser printers, and fax machines. Now, though, scientists at AT&T Bell Laboratories have a brighter, faster light-emitting diode (LED) that uses so-called microcavity effects.
The microcavity, a tiny pair of mirrors less than one-thousandth of a millimeter apart, traps photons so that light is emitted in one direction. In the Aug. 12 issue of Science, the Bell Labs team announced a resonant-cavity LED that's five times as bright as today's LED. They also demonstrated the possibility of making one 10 times as bright and twice as fast. Of course, that's just 10% the brightness and speed of a laser. But lead author E. Frederick Schubert says that's good enough for short-distance fiber communications, such as between workstations in a building, as well as for laser-quality printers and fax machines. He estimates the LED could cost one-fifth as much as a laser and last 10 times as long.EDITED BY RUTH COXETER