LONG-DISTANCE TRANSMISSION EXPERIMENTS USING THE WDM TECHNOLOGY

The wavelength division multiplexed (WDM) technology is useful to util ize the vast bandwidth of the optical fiber, and it should be one key to overcome the transmission capacity problems of the future broadband communications such as multimedia services, Until the optical amplifi ers were developed, only the short distance (up to a few tens kilomete rs) WDM system was in focus, because the optical repeaters for the WDM transmission were considered to be not practical, The advent of the o ptical amplifiers made it possible to construct the long distance (mor e than several hundreds kilometers) WDM systems, and many demonstratio ns of the long distance WDM transmission have been reported up to toda y, This paper describes the recent results of the long distance transm ission experiments using the WDM technology, A few examples of the lon g distance transmission experiments using WDM technology is presented, As the four-wave mixing (FWM) is the substantial limiting factor of t he WDM transmission, these system demonstrations adopt the method to r educe the FWM effect, The stability of the performance is another sign ificant concern to design a practical system, Therefore, the experimen tal study of the WDM system stability is also discussed.