This article is one in a series of 10 stories we're running this week covering today's most significant emerging technologies. It's part of our annual "10 Emerging Technologies" report, which appears in the March/April print issue of Technology Review.

Researchers trying to make high-capacity DVDs, as well as more-powerful computer chips and higher-resolution optical microscopes, have for years run up against the "diffraction limit." The laws of physics dictate that the lenses used to direct light beams cannot focus them onto a spot whose diameter is less than half the light's wavelength. Physicists have been able to get around the diffraction limit in the lab--but the systems they've devised have been too fragile and complicated for practical use. Now Harvard University electrical engineers led by Kenneth Crozier and Federico Capasso have discovered a simple process that could bring the benefits of tightly focused light beams to commercial applications. By adding nanoscale "optical antennas" to a commercially available laser, Crozier­ and Capasso have focused infrared light onto a spot just 40 nanometers wide--one-­twentieth the light's wavelength. Such optical antennas could one day make possible DVD-like discs that store 3.6 terabytes of data--the equivalent of more than 750 of today's 4.7-gigabyte recordable DVDs.