The use of higher-order modes of chalcogenide fibers for optimizing the method of the mid-IR evanescent wave spectroscopy

Based on a theoretical approach, new for evanescent wave spectroscopy, it has been shown that the dispersion properties of higher modes of a multimode chalcogenide fiber partially immersed in an absorbing medium can be used to create fiber devices that combine the functions of a supercontinuum generator and a sensing element of a spectroscopic sensor of the mid-IR range. The propagation of radiation in higher modes will allow one to control the position of the group velocity dispersion zero and to obtain a supercontinuum pumped in the near IR range. In the sensing element, the use of higher-order evanescent modes will allow for greater sensitivity and broaden the dynamic range of the sensor.