Multi-gas sensing with quantum cascade laser array in the mid-infrared region

Wide tunable lasers sources are useful for spectroscopy of complex molecules that have broad absorption spectra and for multiple sensing of smaller molecules. A region of interest is the mid-infrared region, where many species have strong ro-vibrational modes. In this paper a novel broad tunable source composed of a QCL DFB array and an arrayed waveguide grating (also called multiplexer) was used to perform multi-species spectroscopy (CO, C2H2, CO2). The array and the multiplexer are associated in a way to obtain a prototype that is non-sensitive to mechanical vibrations. A 2190-2220 cm(-1) spectral range is covered by the chip. The arrayed waveguide grating combines beams to have a single output. A multi-pass White cell was used to demonstrate the efficiency of the multiplexer.