High quality factor, small mode volume, ring-type plasmonic microresonator on a silver chip

We theoretically propose a microresonator on a silver chip. The microresonator supports hybrid plasmonic modes with highly localized electromagnetic fields (ultra-small mode volumes ~0.1 µm^3) and long photon lifetime (high quality factors >400) at room temperature, both of which exceed the traditional plasmonic microresonators. The total quality factor is found to be limited by two factors, the metal absorption and the radiation loss, and exhibit a tradeoff with the mode volume. This type of hybrid plasmonic microresonators holds great potential in fundamental physics and applications, for instance, cavity quantum electrodynamics in weak coupling regime and low-threshold microlasers.