Stefan is the head of the nanoplasmonics group at Physics Department at Imperial College London.

His research group conducts a wide variety of fundamental and applied research in nanoplasmonics, nanophotonics, and metamaterials, ranging from unravelling light/matter interactions on the nanoscale, to the development of highly efficient optical biosensors, light harvesting nanostructures for photovoltaics, and the development of new materials and devices for photonic nanotechnology.