Optical chips that transmit data on beams of light promise faster and more reliable computing, but they have not caught on widely because they must use expensive, exotic semiconductor materials to emit light: plain silicon won’t do the job. Now a research group led by physicist Salvatore Coffa at STMicroelectronics, headquartered in Geneva, Switzerland, has developed an all-silicon chip that combines both optics and electronics. Parts of the silicon are mixed with special rare-earth elements, which enables them to generate light about 100 times more efficiently than any previous silicon device, according to Coffa. The one-millimeter-square device uses light beams to talk to other chips. The STMicroelectronics chip’s first applications will be in telecommunications and biomedical devices, but it could eventually enable new processors for high-end computers and cheaper lasers and plasma displays. Potential customers will test the chip by the middle of 2004, says Coffa, and it could be incorporated into “billions of devices” by 2007.