Iris Niehues in her Lab at nanoGUNE
© nanoGUNE

Investigating the optical properties
on the nanoscale

Our group focuses on the fundamental optical properties on the nanoscale of 2D materials and single-photon emitters to develop novel functionalities for quantum technology applications. We use near-field techniques to achieve an optical resolution beyond the diffraction limit together with conventional techniques.
The group is funded by the NRW Rückkehrprogramm Quantentechnologie.

Schematic picture of the near-field microscope
© Iris Niehues

Operation of a near-field microscope

Our near-field microscope is based on an atomic force microscope (AFM) equipped with a metal tip. The AFM  is typically used to resolve the morphology of a surface with nanometer resolution. Here, the tip is additionally illuminated with light, and creates a local nanofocus in the size of the tip radius leading to an optical resolution of abut 30nm. The backscattered light is recorded as a function of sample position and gives information on absorption and reflectivity of the sample.
This scattering-type Scanning Near-field Optical Microscope (s-SNOM) is typically used to study phonon-polaritons in 2D materials, to map the carrier concentration, and for nanoscale chemical identification. In addition, our setup is equipped with a spectrometer offering the possibility to detect photoluminescence (PL) and Raman signals.