Special topics in Topological Photonics: Disorder, non-Hermiticity, and non-linearity Alexander Szameit University of Rostock In this Masterclass, we will discuss special topics of topological photonics in more depth. The plan is to discourse three recent topics: The topological Anderson insulator, non- Hermitian topological photonics, and nonlinear Topological insulators. KSOP-QMat Summer School 2020