Application of SPICE simulation to study WDM and SCM systems using EDFAs with chirping

The authors have proposed an equivalent electrical circuit model of erbium-doped fiber amplifiers (EDFAs), including the chirping effect for teaching or studying the distortions and performance of lightwave transmission systems. Through the aid of a SPICE circuit simulator, its validity is demonstrated by analyzing the cross modulations of an eight-channel wavelength division multiplexing system. The intermodulations in an amplitude modulation–subcarrier multiplexing (SCM) system are demonstrated. The channel-number dependence of the composite second-order distortion in a 42-channel SCM system is shown, and its applications to analyze other systems are also discussed.