Comparison between chalcogenide glass single index and microstructured exposed-core fibers for chemical sensing

Chemical bonds of most of the molecules vibrate at a frequency corresponding to the near or mid infrared field. It is thus of a great interest to develop sensitive and portable devices for the detection of specific chemicals and biomolecules for various applications in health, environment, security and so on. A microstructured exposed-core (MEC) fiber has been elaborated for the first time. This design consists of a chalcogenide glass optical fiber with a suspended micron-scale core that is partially exposed to the external environment. This configuration has been chosen to elaborate, using the molding method, a chalcogenide fiber for chemical species detection. The sensitivity of this fiber to detect molecules such as acetone and propan-2-ol has been compared with those of single index fibers. Although evanescent wave absorption is inversely proportional to the fiber diameter, the results show that an exposed-core fiber is more sensitive than a single index fiber having a twice smaller diameter.