Semiconductor optical amplifier is a photonic
device that could be used as linear and non-linear device. The
device in linear mode as amplification at the beginning,
middle and end of the lines and in the case of non-linear
optical fibre as the optical wavelength converter, optical
multi-multiplexer and optical logic gates are used. The most
important applications of this device in non-linear effects of
XPM, XGM, SPM and FWM are discussed in this article.
