Chalcogenide fiber based microresonators as sensing elements of spectroscopic sensors
The mid-infrared (IR) fiber-based evanescent wave spectroscopy is an efficient tool for the real-time chemical analysis of various substances having strong absorption bands of their vibrational spectra in the range of wavelengths of 3 – 10 μm. Chalcogenide fibers have small optical losses in this range. Chalcogenide fiber bases microresonators (MR) can be used as sensing elements of the spectroscopic sensors. In this work, a theoretical model has been developed for analysis of the chalcogenide fiber based MR functionality on the example of determination of two-component liquid solutions concentration. Q-factors of whispering gallery (WG) modes of the MRs have been evaluated with account of the external medium absorption. If the WG modes are excited in MR by a light beam delivered, for example, by another fiber, shape of resonances in the fiber transmittance varies if MR is immersed into an absorbing analyte. By analysis of calibration curves plotted for WG modes with different orders, we have revealed that the sensor sensitivity depends on which modes have been excited in MR. In addition, description of the technology of MR fabrication at a chalcogenide fiber tip is presented.
Saratov State University
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