IEC TR 61292-9:2017(E) which is a Technical Report, focuses on semiconductor optical amplifiers (SOAs), especially the specific features and measurement of gain and polarization dependent gain (PDG). In this document, 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. This second edition cancels and replaces the first edition published in 2013. This edition constitutes a technical revision.  This edition includes the following significant technical changes with respect to the previous edition:
a) addition of new terms;
b) clarification of noise figure definition.
Keywords: semiconductor optical amplifiers (SOAs), gain and polarization dependent gain (PDG)