Rotation and conversion of transmission mode based on a rotatable elliptical core ring resonator

• We study the transmission characteristics of a compact SPPs filter based on ECR resonators.
• We analyze the influences of the eccentricity and rotation angle on transmission modes in detail.
• By rotating the elliptical core, the trannsmission mode of ECR rotates and converts to the corresponding orthogonal mode.
• A 1×2 beam-splitter with tunable splitting ratio is designed based on the ECR resonators.

A compact plasmonic waveguide system consisting of a rotating elliptical core ring (ECR) coupled two metal-insulator-metal (MIM) waveguides is proposed. Influences of the eccentricity and rotation angle of the elliptical core on the transmission characteristics are studied in detail, by using Finite-Difference Time-Domain (FDTD) method. Compared with circular core in ring resonator, the elliptical core will lead to the asymmetric field distributions of intrinsic mode. Based on this, a 1×2 splitter is designed, in which the beam-splitting ratio can be adjusted by changing the eccentricity of the elliptical core. In addition, we find that the intrinsic mode of ECR rotate with elliptical core and gradually convert to its orthogonal mode. Separation of the pair orthogonal modes increases with growth of the eccentricity of the elliptical core. And, the higher order intrinsic mode corresponds to the shorter rotation angle of mode conversion.