IEC/TR 61292-9:2013(E) which is a technical report, focuses on SOAs, especially the specific features and measurement of gain and PDG. In this report, only the amplifying application of SOAs is described. Other applications, such as modulation, switching and non-linear functions, are not covered. Potential applications of SOAs, however, such as reflective SOAs (RSOAs) for the seeded wavelength division multiplexing passive optical network (WDM-PON), are briefly reviewed in Annex A. Keywords: Semiconductor optical amplifiers (SOAs), specific features and measurement of gain, polarization dependent gain (PDG)