y controlled, single-molecule light emitter- demonstrates the rapidly improving understanding of molecular devices. The results also suggest that the unique attributes of carbon nanotubes may be applicable to optoelectronics, which is the basis for the high-speed communi- cations industry. THE FUTURE IS FIBER-OPTICAL TECHNOLOGIES IBM's previous work on the electrical properties of carbon nanotubes has helped establish carbon nanotubes as a top candidate to replace silicon when current chip features can't be made any smaller. Carbon nanotubes are tube- shaped molecules that are 50,000 times thinner than an average human hair. IBM scientists expect today's achievement to spark additional research and interest in the use of carbon nanotubes in nanoscale electronic and photonic (light-based) devices. "By further understanding the electrical properties of carbon nanotubes through their light emission, IBM is accelerating the development path for their electronic applications, as well as possible optical applications," says Dr. Phaedon Avouris, manager of nanoscale science, IBM Research. "Nanotube light emitters have the potential to be built in arrays or integrated with carbon nanotube or silicon electronic components, opening new possibilities in elec- tronics and optoelectronics." IBM's research team has detected light with a wavelength of 1.5 um, which is particularly valuable because it is the wavelength widely used in optical com- munications. Nanotubes with different diameters could generate light with dif- ferent wavelengths used in other applications. IBM's light emitter is a single nanotube, 1.4 nm in diameter, configured into a three-terminal transistor. As in a conventional semiconductor transistor, applying a low voltage to the transistor's gate switches current passing between opposite ends of the nanotube (the device's source and drain). Building on their previous research, IBM scientists engineered the device to be "ambipolar," SO they could simultaneously inject negative charges (elec- trons) from a so