Semiconductor Optical Amplifiers

This chapter contains the basic rules for designing, fabricating, and using semiconductor optical amplifiers. The objective is to explain the influence of SOA design on its main static and dynamic characteristics. In particular, the key role of optical confinement is described, since it determines the level of interaction between photons and carriers. These interactions are then detailed, and the resulting carrier dynamics is studied in details, as it governs most of the performances of SOA, and determines its applicability for practical applications. These applications are then presented, either for linear amplification or for nonlinear operations such as data generation, processing, or routing. Linear applications of SOA require low noise figure, large saturation output power, and large carrier lifetime to limit the addition of linear and nonlinear noise to the amplified signal. On the contrary, SOA should present low saturation output power and carrier lifetime for nonlinear applications. The role of amplified spontaneous emission is evidenced and explained to achieve this.