Faculty Profile of Harald Giessen

Plasmonic materials that consist of nanostructured metals concentrate light on a subwavelength scale. Optical nanoantennas focus light fields into spots of less than 100 nanometers. When arranged in suitable geometries, such plasmonic metamaterials can act as electrical nanocircuits and provide a toolbox to tailor both electric and magnetic light fields which can even result in a negative refractive index and optical cloaks. Chiral plasmonic structures and metamaterials can serve as broadband waveplates and circular polarizers. In combination with suitable surfaces, the nanooptical materials can act as nanosensors that give unprecedented sensitivity and selectivity in the atto- and zeptomolar range, even down to the single monolayer or molecular level. Applications such as hydrogen or glucose sensing based on optical elements have been pioneered in our group. Angle- and polarization independent perfect absorbers can also serve in this role. We manufacture and characterize our nanostructures in our own 600 m2 state of the art nanofabrication facility with electron beam lithography, evaporation and dry etching, as well as nanoscale analysis and imaging capabilities including scanning electron and atomic force microscopy. In our cleanroom we have pioneered three-dimensional stacking of metamaterials, as well as electroless metallization of photonic nanostructures that have been fabricated by 3D direct laser writing. Additionally, colloidal lithography with titled angle evaporation was pioneered by our group to manufacture cm2 sized homogeneous plasmonic structures and metamaterials at extremely low costs.