Mikiya Suzuki, Toshiharu Izumikawa, Katsuhiko Iwashita, Kazutaka Shimoosako, Shinichi Takashima, Toru Yoshikawa, Yasushi Aoyagi and Masaru Fukushima
With the growing use of optical fiber networks Furukawa Electric is working on the development of a full range of optical fiber amplifiers. In recent years wavelength-division multiplexing (WDM) systems have been faced with a need for add/drop capability to allow dynamic change in the number of channels. And the frequent increases and decreases in channels using the add/drop function brings with it rapid changes in the input power level of optical fiber amplifiers. This makes it necessary to have amplifiers that are capable of fast automatic gain control (AGC) to track these rapid changes in input power levels. Further, FTTC or FTTH systems (fiber to the curb or home respectively) have to provide television signal transmission capability in addition to telecommunications. Since TV transmission is generally by analog signals, a necessary specification for optical fiber amplifiers for analog transmission is low signal distortion. This paper reports on two types of compact optical fiber amplifiers that have been developed: the first with fast AGC for transient control, and the second for analog signal transmission.