Fiber-optic acetylene gas sensor based on microstructured optical fiber bragg gratings

A fiber-optic acetylene gas sensor based on a microstructured optical fiber Bragg grating (MOFBG) is presented. The microstructured optical fiber (MOF) is specially designed to have a photosensitive core and holey cladding for grating fabrication and gas detection. The micro-holes of the MOF serve as gas cells, in which the acetylene molecules interact with light through the evanescent-waves of guided modes. The MOFBG with a specific period is utilized to not only make the sensor work in reflection mode, but also selectively determine the wavelength and the order of the acting fiber mode for gas sensing. The MOF is prepared by using the well-known stack-and-draw method, and the Bragg gratings are fabricated by using 193-nm laser pulses. Experiments for the use of the MOFBG for acetylene gas detection have been successfully demonstrated.