Giessen works on ultrafast nano-optics and plasmonics, plasmonic and metasurface sensors, femtosecond two-photon 3D-printed micro-optics (on fiber tips and detectors), widely tunable ultrafast/mid-IR sources for molecular sensing, and Rydberg-exciton quantum optics in cuprous oxide. In the broader landscape of NV-centre ensemble quantum sensing (DEER, nano-NMR, T1 relaxometry) operating near pT/sqrt(Hz) sensitivity, this work sits adjacent as a nanophotonic sensing and light-source enabler.

Herkommer holds the chair for Design and Simulation of Optical Systems at Stuttgart's Institute of Applied Optics (ITO), the group behind much of the optical-design side of two-photon-3D-printed micro-optics -- printing complete multi-lens objectives on the tip of a single-mode fibre, which enables ultrathin endoscopic imaging and micro-objectives that cannot be made by conventional polishing. Related work covers freeform and metasurface optics, aberration theory, and adaptive/computational imaging. Long-running collaboration with Giessen (existing PI) at the 4th Institute of Physics. Relative to the established NV-ensemble quantum-sensing playbook (DEER, nanoscale NMR, T1 relaxometry at pT/sqrt(Hz) ensemble sensitivity), a borderline inclusion on the microscopy axis: the group does not do sensing itself, but it makes the optics that get a diffraction-limited spot into places you otherwise cannot reach -- directly useful for fibre-coupled NV probes and endoscopic quantum sensing.