A New Focus for Light
Researchers trying to make high-capacity DVDs, as well as more-powerfulcomputer chips and higher-resolution optical microscopes, have foryears run up against the "diffraction limit." The laws of physicsdictate that the lenses used to direct light beams cannot focus themonto a spot whose diameter is less than half the light's wavelength.Physicists have been able to get around the diffraction limit in thelab--but the systems they've devised have been too fragile andcomplicated for practical use. Now Harvard University electricalengineers led by Kenneth Crozier and Federico Capasso have discovered asimple process that could bring the benefits of tightly focused lightbeams to commercial applications. By adding nanoscale "opticalantennas" to a commercially available laser, Crozier and Capasso havefocused infrared light onto a spot just 40 nanometerswide--one-twentieth the light's wavelength. Such optical antennascould one day make possible DVD-like discs that store 3.6 terabytes ofdata--the equivalent of more than 750 of today's 4.7-gigabyterecordable DVDs.
Source: technologyreview.comAdded: 19 December 2008