Variation of Transmission Characteristics with Ring Geometry in Plasmonic Add-Drop Ring Resonators

Plasmonic add-drop ring resonator configurations in the nanometer scale with different geometric shapes for the ring are proposed. Using known material modelling techniques, a simulation model is developed using the finite-difference time-domain (FDTD) method to calculate the transmission efficiency of these structures at different wavelengths. The effect of increasing coupling distance between the input waveguide and ring on the transmission efficiency is also simulated and analyzed. It has been observed that the add-drop ring resonators with round-edge square ring and elliptical ring both show higher transmission efficiency than the common circular ring design. Moreover, increasing the coupling distance causes a significant reduction in transmission efficiency for each design. Analysis of the transmission characteristics of the different geometric configurations will allow us to compare their suitability for use as filters, biosensors and other optical applications.