Detection of hazardous substances using broadband-tuneable quantum cascade laser based mid-infrared spectroscopy

Broadband tunable external cavity quantum cascade lasers (EC-QCL) have emerged as attractive light sources for mid-infrared (MIR) “finger print” molecular spectroscopy for e.g. detection and identification of chemical compounds. Compared to Fourier Transform Infrared (FTIR) spectrometers EC-QCLs offer the advantage of a much higher spectral brightness, i.e. high output power within a narrow wavelength interval, as well as a collimated low-divergence output beam, thus enabling e.g. stand-off detection schemes. Here we report on the use of EC-QCLs for spectroscopic detection of hazardous substances. We present stand-off detection of explosives and sensing of hazardous substances in water as two prototypical examples.