Researchers of the Plasmo-Nano-Devices Network have experimentally realized Fabry-Perot type surface plasmon resonators. The resonators are based on monocrystalline silver nanowires with a diameter of about 100 nm. Such resonators could constitute a basic element for a variety of further nano-optical functionalities, as wavelength selectivity or applications in near-field optical lithography and microscopy.

Starting by local optical excitation (a) surface plasmon propagation in the chemically prepared nanowires was straightforwardly demonstrated by means of far-field optical microscopy (b). The near field optical microscopy image in (c) reveals a surface plasmon standing wave pattern. This pattern (d) is directly evidencing that the surface plasmon wavelength in the nanowire is shorthened to about half the value of the exciting light wavelenght.

The resonator characteristics was demonstrated by illuminating the nanowire globally and detecting scattered light from both nanowire ends (a). Analysis of the observed signal modulation (b) from nanowires of different lengths allowed to determine the surface plasmon propagation lenght and the nanowire end face reflectivity.

Images courtesy of J.R.Krenn, Nano-Optics Group, Karl Franzens University Graz, Austria.