“…Among manifold fiber-optic sensors, the fiber-optic microstructure (FOM) sensor, formed by introducing microstructure into optical fiber, is one of the most important devices since it offers unique characteristics of high sensitivity, high resolution, and excellent distributing and multiplexing capabilities. To date, the FOM sensors mainly include fiber Bragg grating (FBG) sensors [1,2], long-period fiber grating (LPFG) sensors [3,4], Fabry-Perot interferometer (FPI) sensors [5,6], Mach-Zehnder interferometer (MZI) sensors [7,8], Michelson interferometer (MI) sensors [9,10], and Sagnac interferometer (SI) sensors [11,12]. Each FOM sensor possesses abundant structures and its fabrication technologies are also various, including chemical etching [13], excimer laser micromachining [14], femtosecond laser micromachining [15], CO 2 laser micromachining [16], focused ion beams (FIB) milling [17], and kinds of coating technologies, just to name a few.…”