Gold Nanoparticles on Waveguides For and Toward Sensing Application

First, a short overview of the sensor activities on surface plasmon waveguide mode coupling via wave vector match in metal-coated channel waveguides as well as in slab waveguides and optical fibers is given. Both monomode and multimode approaches were demonstrated as well as the implementation of Bragg gratings and hollow fibers are described. Then, the use of gold nanoparticles for sensor application in combination with these optical device systems is discussed. At the beginning, a channel waveguide approach with gold nanoparticles is described without taking the typical optical features of gold nanoparticles into account. Then, waveguide devices, which use the localized surface plasmon resonance, an absorption band, intrinsic to gold nanoparticles, and the color changes of gold colloids upon clustering for sensor operation are described. This is achieved on quasi-waveguides, channel waveguides, and on optical fibers. Transmission and reflectance experiments have been performed, either with spectral information or with monochromatic light and pure intensity information. An electro-optical approach is discussed. The activities in photonic crystal sensor are described for planar-waveguide systems and hollow photonic crystal fiber bundles.