ABSTRACT
This chapter illustrates the construction of the optical repeater based on O/E and E/O conversion. Through the binary decision process, one can regenerate the signal, removing the waveform distortion and restoring the power level. Such signal regeneration is performed by optical repeaters, which are periodically placed in the fiber link. Since the repeater includes the 3R functions, namely “reshaping,” “retiming,” and “regeneration". The chapter deals with the principle of operation of the repeater, and discusses the future direction of research and development. The quality of the digital information is maintained over a long distance owing to the 3R functions, because one can eliminate noise and signal distortion at every repeater. However, bit error inevitably occurs through the decision process. The chapter discusses how the bit error occurs through the binary decision process. Since erbium-doped fiber amplifiers (EDFA) have become practical devices, the repeater that employs an EDFA has also been introduced into optical transmission systems.
