Whispering gallery resonators for nonlinear optics and optical manipulation

Identification of Dielectric, Plasmonic, and Hybrid Modes in Metal-Coated Whispering-Gallery-Mode Resonators

“…Dielectric whispering-gallery-mode (WGM) resonators have attracted a lot of attention during the past decade. Their high quality factors ( Q -factors) in combination with relatively small modal volumes make them an ideal platform for plenty of photonic applications, ranging from low-threshold microlasers − to ultrasensitive biosensors, , as well as for fundamental research, e.g., strong light–matter interaction, nonlinear optics, − or cavity quantum electrodynamics. − Whereas modal volumes in high- Q dielectric WGM microcavities are limited by diffraction to values of typically a few hundred cubic wavelengths, their metallic counterparts, surface plasmon polariton (SPP) cavities, can break the diffraction limit. SPP cavities rely on the collective excitation of the electron gas in a metallic structure, which is coherently interacting with the electromagnetic field and sustained at the metal–dielectric interface .…”