Group Nonlinear Optics and Quantum Sensing

Innovative new measurement technologies are at the core of the group’s research: What types of sensors will we use tomorrow? And what sorts of opportunities will this open up? In close cooperation with partners in basic research, the group is working on innovative laser-based measurement principles and methods for spectroscopy. This includes continuous-wave (cw) laser light sources with customized wavelengths for spectroscopy, for which the group has a leading position worldwide, as well as wavelength converters for efficient infrared detection. They expand the possibilities of measurement technology, for example, in gas spectroscopy for investigating combustion processes or in the characterization of components for high-power lasers. In addition, they are used in quantum optics research laboratories and for interferometric holography. Frequency combs, on the basis of which new methods of infrared spectroscopy are being developed, are another example of nonlinear optical light sources.

The group is also active in the field of quantum sensor technology: Pairs of photons with different wavelengths, which are “entangled” in terms of their properties, form the basis of the quantum Fourier transform infrared spectrometer, which is designed to enable particularly sensitive measurements. Alkali atoms in specially prepared spin quantum states, for example, can be used as highly sensitive magnetic field sensors. The team is exploring new fields of application for these sensors in industrial process measuring technology.

Nonlinear optics

  • Optical parametric oscillators – wavelengths tunable from 450 nm to 5 μm with power outputs from 10 mW up to many watts (wavelength-dependent) and a linewidth of less than 1 MHz
  • Frequency doubling – conversion efficiency of over 50 percent
  • MIR-NIR conversion – MIR process data recorded at more than 5000 spectra per second
  • Spontaneous parametric fluorescence for quantum sensors

New spectroscopic measurement techniques

  • Photothermal techniques for highly sensitive absorption spectroscopy in solids and gases
  • Dual-comb infrared gas spectroscopy
  • VIS, NIR, and MIR spectroscopy
  • Spectroscopy for detecting residual absorption in materials down to 1 ppm

Quantum sensor technology

  • Spectroscopy with entangled photon pairs – quantum Fourier transform infrared spectrometer
  • Magnetic field sensors with optically pumped magnetometers – NMR at ultra-low magnetic fields