Bell Laboratories in Murray Hill, N.J., has demonstrated 160-Gb/s, single-channel transmission over 300 km of parent Lucent Technologies' TrueWave RS optical fiber. Next step: expanding the system with dense wavelength division multiplexing. The scientists used an indium phosphide-based, high-speed electroabsorption modulator to increase the spectral efficiency. They used the 1550-nm line from the broadband source as a signal. Benny Mikkelsen, a researcher at Bell Labs, said the system demonstrates the potential of next-generation networks. The challenge, he said, is to increase the bandwidth of fiber in amplified systems to enable the use of more channels.