Fiber Bragg gratings in optical microfibers

Microfiber Bragg gratings (mFBGs) are of great promise due to their compactness, large evanescent field effect, low stiffness, and good flexibility. A lot of researches related to the fabrication and the potential applications of mFBGs in sensing and communication have been made in the past. This review begins from the theoretical analysis based on the mode coupling effect. Then, the fabrication techniques for the refractive index-changed and the structural mFBGs are described. The sensing applications for the measurands of refractive index, force, and magnetic field, and the applications for realizing functional devices, including optical tunable filters, temperature-compensated filters, and Fabry-Perot cavities are discussed.