Alkanethiol-capped gold nanoparticles dispersed in n-dodecane were studied by spectroscopic ellipsometry and were modeled using Mie scattering theory. The refractive index in the visible and near-infrared depended on the volume fraction of gold nanoparticles, in good agreement with the theoretical expectation that such dispersed plasmonic nanoparticles can act as low or tunable refractive index materials at specific optical wavelengths.

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A foldable frequency selective surface (FSS) is introduced that may be tuned by changing the folding state. The FSS comprises periodic elements arranged in an origami-like fashion on a dielectric sheet. By folding and unfolding the FSS, the interaction with the incident field and the mutual interactions between the elements may be altered, resulting in a shift in resonance frequency. A sample design of a tunable FSS folded into a chevron pattern and decorated with cross-shaped copper prints allows a 19% shift of resonant frequency with a change in folding angle of 60 .

We have observed an extremely large electro-optically induced photorefractive effect in nematic liquid crystal doped with single-walled carbon nanotubes and fullerene C60. The effective refractive index change coefficient can be as large as 7 cm2/W, which is >1000 times larger than previous observations. We describe the basic mechanisms and conditions necessary for occurrence of such nonlinearities.