Controlling the direction of propagation of surface plasmons via graded index effective dielectric media

In this work, we propose a mechanism to steer and tailor surface plasmon propagation by using graded index concepts. In this approach, a block of dielectric with fixed thickness is placed on top of a semi-infinite metal. The beam steerers are then designed by simply changing the height of the dielectric in the direction perpendicular to the propagation axis. The analytical design is presented and several structures are evaluated with the ability to steer the incoming surface plasmons at any desired output angle.