Using Higher-Order Modes of Chalcogenide Optical Fibers for the Optimization of Evanescent Wave Mid-IR Spectroscopy

Abstract

On the basis of a new theoretical approach that is proposed for solving tasks of the evanescent wave mid-IR spectroscopy, it is shown that the dispersion properties of higher-order modes of a multimode chalcogenide optical fiber partly immersed into an absorbing medium can be used for the creation of fiber-optic devices combining the functions of a supercontinuum generator and a sensing element for mid-IR spectroscopic sensors. The propagation of radiation in higher-order modes makes it possible to control the position of zero dispersion of group velocity and to generate supercontinuum with near-IR pumping. Using higher-order evanescent modes in a sensing element, it will be possible to increase its sensitivity and expand the dynamic range.