Excitation and propagation of surface plasmon polaritons on the gold covered conical tip

The phenomenon of resonant excitation of surface plasmon polaritons (SPP) at the gold covered conical tip of an optical fiber is considered. The SPP mode is excited by the energy of the waveguide mode. The SPP resonant excitation condition is realized at the presence of an additional transparent dielectric coating of certain thickness on the metal surface. During the experiment, we detected an output radiation from the tip when the tip came out of the liquid (glycerin). The peaks of output optical intensity are obtained. This is explained by the resonant excitation of SPP due to the formation of a liquid layer in the form of meniscus surrounding the tip. This mechanism of SPP excitation in the region of the tip of the optical waveguide opens up new possibilities for increasing the resolution of the nanometric scanning optical microscope. (c) 2005 Elsevier B.V. All rights reserved.