Signal Processing Applications Of Fiber-Optic Delay Lines

In recent years, considerable progress has been made in the development of components for wideband optical communication, using glass fibers as the transmission medium. (I") The most dramatic advance has been in the loss in the fibers themselAes, which has dropped from a minimum of about 1000 dB/km prior to 1970 to 0.2 dB/km today.(') Similarly, research in the field of integrated optics has led to the development of miniaturized, single-mode com-ponents for use with laser sources. Generation, modulation, directional coupling, switching, and detection of light are functions which have already been demonstrated with integrated optics devices.('-') Improvements in bandwidth, switching and multiplexing capability, size, and reliability for fiber communications systems could result from these efforts.