With optical fiber capacity increasing by a factor of two every year, wavelength division multiplexing (WDM) is becoming critical to continued growth of that number. This is what Alastair M. Glass, director of the Photonics Research Labor-atory at Lucent Technologies' Bell Laboratories in Murray Hill, N.J., told attendees during the Orton Memorial Lecture at the American Ceramic Society's annual meeting in April. Glass predicted that commercial optical fiber soon will be handling a terabit of information. The World Wide Web is the primary cause: From 1995 to 1998 the number of Web users increased almost sevenfold to more than 40 million; the number of servers jumped from 100,000 to more than 3 million; the monthly traffic increased by several orders of magnitude to 3000 TB; and the Internet backbone demand is doubling every six months. WDM now forms the basis of flexible optical networking for wide area networks, metropolitan area networks and local area networks. The residential access network is the next challenge, and Glass predicted that significant progress in this area will occur over the next several years. For continued penetration, low-cost optical components will be required. The progress in optical network systems is dependent on the components. Next-generation components that will be needed include 1000 x 1000 optical cross-connects, wavelength-selectable lasers, reconfigurable add/drop multiplexers, wavelength monitors, tunable WDM couplers, ultrabroadband amplifiers, dynamic gain and dispersion equalizers, in-line optical spectrum analyzers, and high-capacity elements for network management. At this point, many of these devices exist only in the research lab.