Research

General Research Activities

The research activities of the Laboratory for Laser Spectroscopy and Sensing generally focus on fundamental aspects and applications in monitoring and analysis of trace gases by employing laser spectroscopic techniques. Trace gases play a key role in many important areas ranging from atmospheric chemistry, industrial process surveillance, agriculture to medical diagnostics.

New research areas concern noninvasive glucose detection in human tissue and the analysis of drugs in saliva.

We address the key issues for sensing by basic research on molecular spectroscopic data and algorithms for spectral data analysis, and by development and implementation of various laser sources (e.g. difference frequency generation, quantum cascade lasers) and novel concepts (e.g. fiber optic cavity sensors) in combination with various detection schemes (photoacoustic, photothermal, multipass absorption, cavity-ringdown and attenuated total reflection (ATR)).
Laser spectroscopic schemes include a mobile system for in situ measurements and several laboratory-based devices. As laser sources two cw sealed-off CO₂ lasers with different isotopic fillings (¹²CO₂ and ¹³CO₂), a broadly tunable 10 µm quantum cascade laser with external cavity, broadly tunable pulsed and cw diode-based compact difference-frequency sources, as well as external cavity near-infrared diode lasers are employed. In addition Fourier-transform infrared (FTIR) spectroscopy in combination with ATR is used for studying fluids. This selection gives a large flexibility for applications with respect to accessible wavelength range, tunability, power and linewidth.

Individual research projects include the study of photothermal diffuse reflectance, determination of isotope ratios in gas mixtures, a new approach for non-invasive determination of glucose in tissue, studies on surgical smoke, breath analysis for medical diagnostics, the analysis of doping agents in urine samples, and of drug traces in saliva. Finally, an LED-based low-cost gas sensor and a sensitive infrared absorption laser sensor are being developed.
The funding by the Swiss National Science Foundation, by ETH Zurich, industrial partners and private funding agencies is gratefully acknowledged.