Nanotechnologies and nanofabrication techniques provided unmeasureable possibilities to control intrinsic microscopic features of materials and structures in the last years. In particular, materials optical properties and light propagation control have been some of the most challenging problems due to their various application possiblities. The present investigation shows that temporally coherent thermal sources have been successfully designed and optimized with evolutionary optimization methods such as genetic algorithms and particle swarms. This lead to a bilayer structure of germanium and silicon carbide, which is, to our knowledge, the simplest existing structure with such properties.