The outlook for new technology

Snell's Law gives the relationship between the angles of incidence and refraction for a light ray crossing from one medium into another. Since Dutch mathematician Willebrord van Roijen Snell (1580 to 1626) delineated the law in 1621, all known materials have exhibited positive indices of refraction.

That situation changed recently when independent teams at MIT (Massachusetts Institute of Technology) and Boeing Phantom Works created materials that demonstrate negative refraction (Picture). In addition to ending a long debate over whether negative refraction violates the laws of physics (it doesn't), the results also dangle the enticing possibility of lenses capable of subwavelength focusing. Such lenses could revolutionize applications such as photolithography and optical storage.

Both research teams observed negative refraction of microwaves through composite materials that feature metal rings and wires arranged in grid patterns on pc-board substrates. However, researchers will have to surmount many challenges before negative refraction makes an impact on commercial applications. For example, both teams noted significant attenuation, which may or may not be a fundamental characteristic of negative-index materials.

A team at Xerox has developed a MEMS-based photonic switch that duplicates the functions of an R-OADM (reconfigurable optical add/drop multiplexer)—a device that's 10 to 100 times larger than the switch. The chip compresses an R-OADM into a space measuring 2×1.5-cm and also does away with the manual-alignment tasks that make conventional optical systems difficult to configure. Constructed on a single silicon wafer using conventional processing techniques, the device features planar waveguides about 5 to 6 microns wide. Because of its size, low cost, and remote-configuration capabilities, the device could help improve the economics of extending fiber-based networks through the "last mile" to homes and businesses.

Electronic-paper technology is supposed to lead to high-resolution displays that are thin and flexible enough to roll up like sheets of the real stuff. We may have to wait awhile for such products, but the technology is making progress. At the recent Society for Information Display expo in Baltimore, Philips and E Ink showed engineering samples of a display with 160-pixel/in. resolution—higher than anything the companies have showed before (Picture). Philips designed the display's thin-film-transistor backplane and driver electronics. E Ink contributed the electronic-ink technology, which features microcapsules that contain electrically charged white and black particles suspended in a liquid. The particles respond to an electric field by moving to the top or the bottom of the capsule, depending on the charge, thus creating either a black or a white pixel. The companies say they are on track for mass production early next year.

Avid moviegoers sing the praises of Texas Instruments' DLP (digital-light-processing) chip, which features an array of tilting micromirrors and finds use in digital-projection systems that win acclaim for their ultracrisp images. Now, a research team at the University of Texas Southwestern Medical Center has adapted the same chip for use in a projector that creates moving holographic images. The team has sent 3-D images of helicopters and other aircraft flying through a gel-filled tank that serves as a display medium. Possible applications include heads-up displays for pilots and, once resolution improves, computer games and medical imaging.