Excitation of a one-dimensional evanescent wave by conical edge diffraction of surface plasmon

The experimental observation of a one-dimensional evanescent wave supported by a 90 degrees metal edge is reported. Through a measurement of in-plane momenta, we clearly demonstrate the dimensional character of this surface wave and show that it is non-radiative in the superstrate. Excitation conditions, lateral extension and polarization properties of this wave are discussed. Finally, we explore the effect of the surrounding dielectric medium and demonstrate that a single edge can sustain distinct excitations. (C) 2011 Optical Society of America