Exceptional points enhanced sensing in a whispering-gallery-mode resonator (Conference Presentation)

In this talk, I will discuss the sensitivity enhancement in a whispering-gallery-mode resonator operating at the exceptional points. The exceptional points are obtained by controllably introducing two scatterers within the mode volume of a whispering-gallery-mode resonator. A nanofiber tip is used to mimic a nanoparticle to study the sensitivity enhancement of the resonator operating at the exceptional points. I will present the experimental results demonstrating that the resonator operating at the exceptional points exhibits square-root enhancement in frequency splitting when compared to a single resonator subject to the same amount of perturbation. The dependence of sensitivity enhancement on the angular position and size of the nanofiber tip is also studied. The experimental results agree well with the theoretical predictions and numerical simulations. Our study shows the potential applications of the resonator operating at the exceptional point for ultrasensitive single nanoparticle and biomolecule detection.