Manipulating Surface Plasmon Polaritons in a 2-D T-Shaped Metal–Insulator–Metal Plasmonic Waveguide With a Joint Cavity

A 2-D T-shaped metal-insulator-metal plasmonic waveguide with a joint cavity is introduced. The field distribution of the structure is investigated by using the finite-difference time-domain (FDTD) method. It is found that the surface plasmon polaritons' splitting ratio changes periodically as the joint cavity is moved. The period and maximum for the splitting ratio increase with increasing the width of the joint cavity. The results of the splitting performance obtained by the FDTD agree well with our semi-analytic model based on the scattering matrix theory.