Optical mode confinement in three-dimensional Al/SiO_2 nanocavities with hyperbolic dispersion

摘要

Today's technological needs are demanding for faster and smaller optical components. Optical microcavities offer a high confinement of electromagnetic field in a small volume, with dimensions comparable to the wavelength of light, which provides a unique system for the enhancement of light-matter interactions on the nanoscale. However, further reducing the size of the optical cavity (from microcavity to nanocavity) is limited to the fundamental diffraction limit. In hyperbolic metamaterials, large wave vectors can be achieved. Therefore, optical cavities, created from hyperbolic metamaterials, allow the confinement of the electromagnetic field to an extremely small volume with dimensions significantly smaller than the wavelength of light. This paper presents the results of numerical study of the optical mode confinement in nanocavities with hyperbolic dispersion using nanolayered Al/SiO_2 hyperbolic metamaterial with different Al fill fractions. The fundamental properties of the optical modes and resonance frequencies for the nanocavities are studied using the finite-element-method numerical technique. Numerical simulations show that the light can be well confined in a disk with radius up to λ/65. This paper will also focus on other variables such as Q-factor and Al fill fraction. Potential future applications for three-dimensional nanocavities with hyperbolic dispersion include: silicon photonics optical communications networks, ultrafast LEDs and biological nanoparticles sensing.