Hybrid plasmonic ring resonator at subwavelength scale in the visible spectrum

Abstract

In the past decade, plasmonic resonators have emerged and exploited field compression to create ultrasmall mode volume devices and to enhance light–matter interactions. We devised a ring resonator on a metal substrate separated by a low-permittivity dielectric, which supports hybrid plasmonic modes with a highly localized electromagnetic field. The finite difference time domain method was used to calculate the properties of the ring resonator. By changing the cavity’s geometry and low-permittivity dielectric’s height, a high-quality factor along with ultracompact mode confinement was achieved, leading to Purcell factor as high as 2.7×10 4 . The hybrid plasmonic ring resonator exhibits a trade-off between the high-quality factor and the ultrasmall mode volume at subwavelength scale in the visible spectrum.