SummaryThe concept of guided lightwave communication along optical fibers has stimulated a major new technology over the past two decades. This technology profoundly impacts communication and instrumentation systems as well as computer interconnections and system architecture.In this paper the state of the art of optical transmitters, low loss fiber waveguides, receivers and associated electronics components are reviewed and summarized for optical data transmission systems operating between 100 Mbit/s and 2.5 Gbit/s. Emphasis is placed on high speed data transmission subassemblies, such as time division multiplexers and demultiplexers, clock and data recovery circuits, as well as optical transmitters and receivers. In addition, the performance of candidate components of the wide band digital transmission systems intended for deployment in large detection systems for particle physics is discussed.