Current Research Topics

The general interest of the nano-optics group is in light-matter interactions on the subwavelength scale.

Optical Antennas
Optical antennas are devices that enhance the local light-matter interaction. We use optical antennas to improve the quantum efficiency of single quantum emitters and to engineer their emission properties.

Near-field Optics
Optical near-fields are characterized by non-propagating evanescent fields. They are being studied for high-resolution microscopy and spectroscopy, for sensing, and for optical manipulation.

Nonlinear Plasmonics
Metals and their interfaces exhibit high nonlinear optical coefficients. We study the nonlinear properties of metal nano structures for applications such as on-chip wavelength-conversion, optical modulation, and single-photon switching.

Vacuum Trapping and Cooling
We optically trap single nanoparticles in high vacuum and cool their center-of-mass motion to low temperates by active or dynamic back-action. Vacuum trapped nanoparticles exhibit very high quality factors (Q > 107), which makes them attractive for ultrasensitive detection and metrology.

Nanocarbon Photonics
Due to their unique bandstructures and dispersion relations carbon nanotubes and graphene exhibit very attractive optoelectronic properties. We use tip-enhanced Raman scattering and tunneling microscopy to study the influence of local defects and dopants in nanocarbon materials.

Near-field Quantum Optics
Near-fields are bound to their sources and cannot be quantized following standard procedures. 
A measurement of the near-field necessarily alters the near-field and affects the source. This problem is rooted in so-called measurement back-action and limits the ultimate measurement sensitivity.

Nano-Optofluidic Detection
We use nanofluidic channels in combination with optical interferometry to detect and recognize single nanoparticles in real-time and label-free.  We are able to detect and sort single viruses, larger proteins, and impurities in fluids.