Erbium-doped fiber amplifiers for ultrashort pulse generation and optical soliton communication

Abstract

In 1989 it was shown for the first time that erbium-doped fiber amplifiers1 (EDFAs) are useful for soliton amplification and transmission2; it was also shown that the lumped amplifier technique using EDFAs made it possible to move the dream of soliton communication into an actual developmental stage.3 Our technique, dynamic soliton communication, also known as the guiding center soliton or super soliton,4 has a wide range of use from L a ≪ Zsp to L a ~ Zsp depending on the maximum required transmission distances. Here L a and Zsp are the repeater spacing and the soliton period. However, when we seriously compare the cost/bit of linear high speed IM/DD or coherent systems and the present soliton system, the extension of the repeater spacing becomes crucial. We describe single-pass soliton transmission at 10 Gbit/s over 1000 km with a 50-km repeater spacing. Furthermore, 20 Gbit/s over 500 km experiment, in which a nonlinear soliton interaction occurs, is presented. With the aid of EDFAs, soliton technologies such as soliton switching using nonlinear (amplifying) loop mirrors and amplification and generation of femtosecond solitons have sufficiently matured. Applications of EDFAs to these areas are presented.