Theoretical Description of Dynamic Transmission Characteristics in MDM Waveguide Aperture-Side-Coupled with Ring Cavity

We investigate the dynamic transmission characteristics in metal-dielectric-metal (MDM) waveguide aperture-side-coupled with ring cavity. Assuming the aperture as a resonator, a theoretical model was established to describe the formation and evolution mechanisms of the spectral responses in circular ring structure, and the theoretical results are in good agreement with the finite-difference time-domain (FDTD) simulations. In particular, combining Maxwell's equations and field distributions, the analytical theory is also applicable to other aperture-side-coupled ring nanostructures, which highlights the utility of the theoretical description. The results may pave the way towards controlling light in highly integrated optical circuits.