Semiconductor Optical Amplifier

Semiconductor optical amplifiers (SOA) are made using semiconductors (e.g., InGaAsP). The basic principal behind optical amplification is stimulated emission. In order to have stimulated emission, population inversion is needed, which is created by electrical bias in SOA. The gain and noise in these are modelled by the following equations

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

and

$$S_{sp} = n_{sp} h \nu \left ( G -1 \right ) \hspace{0.5in} watts/Hz.$$ (2)

In the above eqautions, G is SOA gain, G₀ unsaturated gain, P_in input power to SOA, P_sat saturation power level, S_sp amplifier sponataneous emission (ASE) noise power spectral density, n_sp spontaneous emission factor, h Plank's constant, and $\nu$ optical frequency.

In the next section the placement algorithm of the OAs is given and thereafter main results are discussed.