Bright Mid-Infrared (MIR) Photoluminescence Sources and their Application in Imaging and Sensing

Mid-infrared (MIR) spectroscopy and imaging underpin many applications, ranging from industrial process monitoring to environmental analysis, and offer a new era in healthcare and clinical diagnostics. The spectral region from 1.5 to $12\ \mu \mathrm{m}$ is of interest since it contains strong characteristic absorption peaks associated with the vibrational transitions of many important molecules. A principal requirement for rapid measurement is bright, fibre-based, sources that, if possible, should also be robust and low cost. This paper describes our work to use sources based on the photoluminescence from Pr3+ and Dy3+ doped GeAsGaSe fibres to provide affordable carbon dioxide (CO 2 ) sensing in heritage buildings. Limitations to the Beer Lambert law, previously reported by others, were observed in the sensing system, and the sensors were consequently calibrated empirically. Simulation results show that the use of commercial filters provides a promising approach to realising more compact, real-time, sensing.