Negative refraction of a surface plasmon polariton

We study theoretically the negative refraction of a surface plasmon polariton. The system we consider consists of a vacuum that is in a contact with two metals that each fill a quarter space with a periodic boundary between them. The interface of each of the metals with the vacuum supports a surface plasmon polariton. When a surface plasmon polariton passes through the periodic boundary between the metals it transforms partly into the Bragg beams of the refracted and reflected surface plasmon polaritons and partly into volume waves in the vacuum. A suitable choice of the period can ensure that the only propagating Bragg beams of the refracted surface plasmon polariton are the specular beam and the (−1)-order beam, which is negatively refracted. With a suitable choice for the form of the profile function and its amplitude the specular beam can be made to vanish.

Research highlights▶ A simple planar surface structure is described that refracts negatively a surface plasmon polariton incident on it. ▶ The negative refraction can occur for almost all angles of incidence of the surface plasmon polariton. ▶ The refraction problem is solved by the use of an impedance boundary condition and the Wiener-Hopf method.