Microfiber technology has great potential in numerous applications as microfibers possess a number of unique characteristics and optical properties. Recently, there is an increasing interested in the research of microfibers and microfiber structures. In this book, the background theory and fabrication techniques of microfiber devices are presented. Throughout this research degree, a high precision computer-controlled microfiber workstation based on flame brushing technique was constructed. A workstation that is capable of producing low loss tapered fibers. In our record, we have attained microfibers with maximum length of ~230mm and a smallest diameter of 400nm. Several optical structures such as Microfiber Loop Resonators, Microfiber Knot Resonators and Microfiber Mach-Zehnder Interferometer were assembled and studied. The investigation of microfiber structures in applications of laser generation, temperature sensing, and electric current sensing is also presented. This is a good book for beginners in the research of optical microfiber technology.