Wavelength-Selective Optical Filters Based on Metal-Patch Cavities With Slot Waveguide Interfaces

We theoretically propose and investigate the resonant wavelength-selective optical filters based on the subwavelength metallo-dielectric nanopatch cavities and the metal slot waveguides. Using the temporal coupled-mode theory and three-dimensional finite-difference time-domain simulations, we analyze the optical coupling efficiencies and filtering characteristics, which are optimized by adjusting the waveguide-cavity distance to modify the decay rates from the cavity. The proposed optical filters can be extended to multiport channel-dropping filters while maintaining subwavelength-scale dimensions including the coupling regions.