Multimode Chalcogenide Fibre Based Platform for the Mid-IR Evanescent Wave Spectroscopy of Liquids

Development of distant real-time analysis of substances content by means of the fiber-based evanescent wave mid-IR spectroscopy encounters many problems such as fragility of few-mode chalcogenide fibers with sub-wavelength-size core, limited power density of radiation in the few-mode fibers, large coupling losses between sensing elements and the few-mode fibers. Using of multimode chalcogenide fibers provide a solution that is discussed in this paper. Examples of numerical characterisation of multimode fibers prove their suitability for combined functionalities as sensing elements and nonlinear frequency converters in the fiber-based sensors.