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| In the past decade, plasmonic resonators have emerged and exploited field compression to create ultra-small mode-volume devices and to enhance light-matter interactions. We propose a ring resonator on metal substrate separated by low-permittivity dielectric, which supports hybrid plasmonic modes with highly localized electromagnetic ?eld. Finite difference time domain (FDTD) method is used to calculate the properties of the ring resonator. By changing the cavity's geometry and low-permittivity dielectric's height, high quality factor of 354 along with ultra-compact mode confinement 0.0078 (λ/2n)3 ~ 0.0001um3 is achieved, leading to Purcell factor up to 2.7 x 104. Moreover, the mode volume remains of the order of 0.01(λ/2n)3 with quality factor bigger than 100 for a ring radius and thickness in the range of nanometers. The hybrid plasmonic ring resonator exhibits a trade-off between the high quality factor and the ultra-small mode volume at deep subwavelength scale in the visible spectrum. It holds great potential in fundamental physics and applications in photonics and optoelectronics, for instance, cavity quantum electrodynamics in weak coupling regime and low-threshold lasers. |
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| Keywords:ring resonator, hybrid plasmonic, deep subwavelength, visible spectrum |
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