Optical Amplifier

An optical amplifier works on principal of stimulated emission. They are mainly of two kinds, semiconductor optical amplifier (SOA) and doped fiber amplifiers (DFA). In this study, SOAs have been considered. The SOA is basically modelled by equations for amplifier gain saturation and amplified spontaneous emission (ASE) noise power spectral density (psd). The gain of SOA is given by

$$G = G_0 \exp \left ( - (G-1) {P_{in} \over P_{sat}} \right ),$$ (3)

and ASE noise psd by

$$S_{sp} = n_{sp} (G-1) h \nu \hspace{0.5in} Watts/Hz.$$ (4)

In these equations, G₀ is unsaturated gain, P_sat, the saturation power level, n_sp, the spontaneous emmission factor, h, the Plank's constant, and $\nu$, the optical frequency.