Fano resonance in whispering gallery mode microcavities and its sensing applications.

• This work gives a comprehensive review of the Fano resonance in WGM resonators especially for sensing in recent years. • The development directions in the future are predicted. • This review provides insightful thoughts of Fano resonance in WGM sensing applications to the audiences who are not familiar with this area. With the advantages of high quality factor (Q) and small mode volume, whispering gallery mode (WGM) microcavities obtain lower detection limits and have been increasingly applied to the detection in physics, chemistry, and biology. The Fano resonance phenomenon, which could further improve the sensing performance in the sensitivity and detection limits because of its sharp change in phase and amplitude, has attracted wide attention and demonstrated that it could be achieved in whispering gallery mode resonators (WGMRs). Fano effect is caused by the interference between the discrete mode and the continuous mode and then shows it in the spectrum. In this paper, first, the relevant knowledge of the WGM resonator and the resonance phenomenon are introduced in detail. Second, the theory of Fano resonance is analyzed. Third, the generation methods and sensing applications of Fano resonance in WGMR in current are summarized. Finally, the existing problems and development prospects of this sensor are discussed. [ABSTRACT FROM AUTHOR]