Cover story: Ding Z X, Chen Y, Xu F. Optical microfiber resonator: principle and applications[J]. Opto-Electron Eng, 2022, 49(8): 220006

With the maturation of microfiber fabrication methods, optical resonator based on optical microfibers was demonstrated and developed, such as microfiber loop resonator, microfiber knot resonator and microfiber coil resonator. As an optical coupling device based on evanescent field coupling, microfiber resonator features in low insertion loss, high Q-factor, high finesse, excellent mechanical stability, easy fabrication process, and compatibility with fiber systems, providing broad platform for all-fiberized miniatured devices of probing and modulation.

The research group of Professor Xu Fei from Nanjing University reviewed the field of microfiber resonators—recent progress in the microfiber resonators research fields were summarized, covering fundamental principles and characteristics, fabrication methods and applications of microfiber resonators. The application domains were divided into perspectives of sensing, modulating and lasers. Microfiber-based resonators have excellent optical and mechanical properties, providing a broad platform support for all-fiber, miniaturized detection and modulation applications. Its advantages of low insertion loss, high quality factor, all-fiber compatibility, and easy fabrication, through further combining with external functional materials and various micro-nano processing technologies, make the realization of "fiber ring laboratory" on micro-fiber resonators feasible.