Tilted fiber Bragg gratings (TFBGs) have shown to be a suitable tool for exciting surface plasmon waves in a comparable manner as in typical attenuated total reflection Kretschmann configurations. In this paper we present a comparative analysis of the characteristics of prism and grating configurations for generating surface plasmon resonance (SPR) for 800 and 1550 nm wavelengths. Results indicate that longer wavelength SPR may present advantages in sensing. Recent label-free biochemical sensing results using NIR tilted fiber Bragg gratings with and without SPR coatings demonstrate limits of detection ranging from the nM to the pM range without the need for thermal stabilization.

We demonstrate a new technique for analyzing surface tension of liquids. This is done upon examining the interference signals reflected from a remnant drop pending at the cleaved end of a single mode optical fiber. The resulting interference patterns are fitted to a multimirror Fabry-Perot model yielding information of the drop size. We show that the wetting process of the fiber plays an important role in drop formation; in particular, the drop size can be correlated to the surface tension of the liquid sample. The proposed configuration may render useful for liquids analysis using small sample volume.

Theoretical and experimental results are presented to show that the complex effective index of the modes of optical fibers coated with non-uniform metal coatings of gold, silver, copper, or palladium, with thicknesses between 0 and 20 nm, acquire a greatly enhanced sensitivity to various forms of perturbations. Thickness changes of less than 1 nm can be measured as well as the binding of record low concentrations of chemical and biochemical species.

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