Paul Planken and his group carry out research into how light interacts with different metals and semi-conductors. His research has shown that after being illuminated by an extremely short laser flash, corrugated metal surfaces emit a short far infrared flash of light. This light, also known as terahertz light, is important due to its many applications in industry and beyond, such as in the screening of packaged products and to reveal hidden paint and other layers in paintings. Planken recently discovered that when graphene (a layer of carbon just one atom thick) is applied to such corrugated metal surfaces, the light yield is increased by a factor of 100. Planken achieved this result in collaboration with researchers from Seoul National University. 

In recent years, Plankens' research has focused on new methods for increasing the light absorption of metals and semi-conductors. Scientifically speaking, this is a very challenging task because metals – such as silver – generally reflect a lot of light. Their absorption can be increased significantly by applying structure to the metal at nanometre scale. Knowledge gained in this field can be used in industries where laser light is used, for example to heat metals.

In Amsterdam, Planken will lead a research group at the Advanced Research Center for Nano-Lithography (ARCNL). This recently established centre is a collaboration between the ASML, the Foundation for Fundamental Research on Matter (FOM), the Netherlands Organisation for Scientific Research (NWO), the UvA and VU University Amsterdam.

Planken was awarded a PhD from the UvA for research he carried out at the FOM Institute AMOLF. After this he spent two years doing post-doc work at AT&T Bell Laboratories in the United States and five years at the FELIX (Free-Electron Lasers for Infrared eXperiments) facility of the FOM Institute for Plasma Physics Rijnhuizen. In 2008 Planken was appointed Antoni van Leeuwenhoek Professor at TU Delft, where he also sat on the board of the Imaging Physics Department and on the Technical Physics Board of Studies. He is the founder of the European Optical Society's ‘Focus Group on Terahertz Science and Technology’ and founder and first programme chair of the biennial European conference in this area. In 2007 Planken received a Vici grant from the NWO.