Microstructured optical fiber-based micro-cavity sensor for chemical detection

The studies on microstructured optical fibers (MOF) have drawn considerable interest and played an important role in many applications. MOFs provide unique optical properties and controllable modal properties because of their flexibilities on manipulation of the transmission spectrum and the waveguide dispersion properties. MOFs are especially useful for optical sensing applications because the micro-structured air channels in MOF can host various types of analytes such as liquids, gases, and chemical molecules. Recently, many studies have focused on the development of MOF-based optical sensors for various gases and chemical molecules. We propose a compact, and highly sensitive optical micro-cavity chemical sensor using microstructured fiber. The sensor probe is composed of a hollow optical fiber and end cleaved microstructured fiber with a solid core. The interference spectrum resulting from the reflected light at the silica and air interfaces changes when the micro-cavity is infiltrated with external chemical molecules. This structure enables the direct detection of chemical molecules such as volatile organic compounds (VOCs) without the introduction of any permeable material.