ers will be looking to dramatically improve the strength of their product. "Even very high quality optical fiber is dirt cheap today," he says. "A more likely application is in the auto industry, where rein- forced plastics could replace metal parts and make cars lighter and more fuel efficient." Gupta and his colleagues next hope to study the atomic level structure of glass and learn more about what contributes to strength at that level. 4.3 NANOPHOTONICS A Cornell University researcher is developing microscopic nanophotonic chips-which replace streams of electrons with beams of light-and ways of connecting the devices to optical fiber. Michal Lipson, an assistant professor at Cornell's School of Electrical and Computer Engineering, believes that one of the first applications of nanophotonic circuits might be as routers and NANOPHOTONICS repeaters for fiber-optic communication systems. Such technology, she notes, could speed the day when residential use of fiber-optic lines becomes practical. Previous nanoscale photonic devices used square waveguides-a substitute for wiring-that confine light by total internal reflection. But this approach works only in materials with a high index of refraction, such as silicon, because these materials tend to reduce light intensity and distort pulses. Lipson has discovered a way to guide and bend light in low-index materials, including air or a vacuum. "In addition to reducing losses, this opens the door to using a wide variety of low-index materials, including polymers, which have interest- ing optical properties," Lipson says. Using equipment at the Cornell Nanoscale Facility, Lipson's group has manufactured waveguides consisting of two parallel strips of a material with a high refractive index. The strips were placed about 50 to 200 nm apart, with a slot containing a material of much lower refractive index. In some devices, the walls are made of silicon with an air gap, whereas others have silicon dioxide walls with a silicon gap. In both cases, the index of refraction of th