Our laser research team is based in Zurich and was originally founded as a spin-off from ETH Zurich. The team develops mid-infrared broadly tunable laser modules and these laser sources are specifically designed for the precise and fast analysis of multi-component gas mixtures, including flammable and toxic gases. The laser uses a Vertical External Cavity Surface Emitting Laser (VECSEL) setup. VECSELs have many advantages over other laser types, especially when compared to edge emitting lasers. They exhibit attractive beam properties such as a radial symmetric energy distribution with a very narrow divergence angle. The emission at a single wavelength can be tuned reliably over a very broad spectral range.
Two highly reflective Distributed Bragg Reflectors (DBR) define the cavity. The light-generating active layers are based on IV-VI semiconductors. These lead-salts are very well suited for the fabrication of opto-electronic devices in the mid-infrared. Their low Auger recombination rate allows room temperature operation, and the direct band-gap ensures high light generation efficiency. The devices are optically pumped through the top DBR, the generated mid-infrared laser light is emitted through the bottom DBR. Optical pumping prevents material degradation and thus ensures long lifetimes. Due to the short cavity length of 20-100 µm, only one longitudinal resonance mode is lasing. By changing the cavity length using a MEMS micro-mirror or a piezoelectric crystal, the single emission wavelength can be shifted continuously over a broad spectral range.
These mid-infrared laser modules are specifically designed for the precise and fast analysis of multi-component gas mixtures, including flammable and toxic gases. The single-mode tuning of the laser wavelength permits the rapid sampling of a full spectrum, from which the concentrations of multiple gases can be derived at once. Such a miniaturized high-resolution spectrometer ensures reliable sensing solutions even in uncontrollable real-world environments.