Applications of fiber-optic evanescent wave spectroscopy.

The evanescent wave (EW) component of light propagated via fiber-optic wave-guides can be used to both sense and transmit information regarding the immediate environment of the fiber's surface. In this article, an outline of the theoretical and practical aspects of this emerging methodology is given, as well as a discussion of the advantages, disadvantages, and limitations of the technique. Examples are given of how EW spectroscopy may be used in the analysis of pharmaceutical systems. Evaluation of attributes of components of EW spectroscopy allows prediction of the future for this rapidly evolving area of photonics.