Evolutionary processes and applications of microfiber resonant Rings: A systematic exploration for sensitivity enhancement

As an all-fiber structure, the microfiber resonator ring (MFRR) has been widely studied due to its high coupling efficiency, large proportional evanescent field, and good compatibility with fiber optic systems. Material sensitization and structural sensitization, as the two most effective sensitization mechanisms, has been the focus of research in fiber optic sensors field. In this review, the evolution and development of MFRR sensitization mechanisms are comprehensively reviewed in terms of the two approaches mentioned above, respectively, with MFRR as the object of study. In particular, we have also systematically investigated the properties and applications of three-dimensional structured microfiber coil resonators, demonstrating their great potential for applications. Furthermore, the preparation and encapsulation methods of MFRR are summarized, the direction of performance optimization during the production of MFRR sensors is analyzed, and the prospects of MFRR sensors are envisaged.