  In this work, we compare the performance of plasmonic waveguide integrated
stub resonators based on 2D metal-dielectric-metal and 3D slot waveguide (SWG)
geometries. We show that scattering matrix theory can be extended to 3D
devices, and by employing scattering matrix theory, we provide the guidelines
for designing plasmonic 2D and 3D single-stub and double-stub resonators with a
desired spectral response at the design wavelength. We provide transmission
maps of 2D and 3D double-stub resonators versus stub lengths, and we specify
the different regions on these maps that result in a minimum, a maximum, or a
plasmonically induced transparency shape in the transmission spectrum.
Radiation loss from waveguide terminations leads to a degradation of the 3D
SWG-based resonators. We illustrate improved waveguide terminations that boost
resonator properties. We verify our results with 3D finite-difference
time-domain (FDTD) simulations.
