“…Four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) has several important features, such as, high speed and high FWM conversion efficiency as well as optical demultiplexing (DEMUX) (Mecozzi et al, 1995;Das et al, 2000). The are several applications of FWM in SOAs for all-optical devices, such as, wavelength converters (Vahala et al, 1996), optical samplers (Inoue & Kawaguchi, 1998), optical phase conjugators (Kikuchi & Matsumura, 1998) and optical multiplexers/demultiplexers (Kawanishi et al, 1997;Kawanishi et al, 1994;Morioka et al, 1996;Uchiyama et al, 1998;Tomkos et al, 1999;Kirita et al, 1998;Buxens et al, 2000) have been demonstrated for optical communication systems. When a pulse of a time-multiplexed signal train (for example, a probe pulse) and a pump pulse are injected simultaneously into an SOA, gain and refractive index in the SOA are modulated and an FWM signal is generated by the modulations.…”