Surface plasmon polaritons on curved surface

We experimentally demonstrate the influence of the mean curvature on the propagation dynamics of surface plasmon polaritons (SPPs) in curved space. In contrary to a classical particle whose motion depends only on the local (Gaussian) curvature of the surface, here, owing to the wave properties of the SPPs, its propagation dynamics also depends on the mean surface curvature. We experimentally observed a new guiding mechanism, based on a geometric potential achieved by the surface curvature for a book-cover surface, while in the case of an inverse book-cover, which has the same local curvature but an inverted mean curvature, the SPPs are rapidly diffracting. Additionally, we show that by longitudinally bending the book-cover, the width of the propagating mode can be dynamically controlled.