Brett Williams's Reviews > Surface Plasmons On Smooth And Rough Surfaces And On Gratings

Raether's book is essential early work (1980s) on what many now properly call surface plasmon polaritons, a hybrid of coupled light or radio waves with evanescent waves emanating from grouped distributions of electrons in metals. The result is spatial amplification of light (focusing) when resonant with plasmons, and more importantly, passage of light through thin metal films (semiconductors are required at RF with lower charge densities and plasma frequency, else negative permittivity is too large).

Raether reviews the various means of light/plasmon coupling including periodic surface features like gratings or roughness, and dielectrics requiring total reflection of incoming light. Raether focuses on he and Kretschmann's design, a prism in contact with a metal film, smooth on the dielectric side, rough on the other, thus incorporating two coupling schemes in one device (and providing options for inventors as the metal appears both as mirror and waveguide allowing signal passage at appropriate incident angles). What "coupling" means here is momentum matching of the k wave-vector component of light along a dielectric/metal interface with that of plasmons in metal, which on smooth surfaces have much shorter wavelengths than light. Without coupling, light will not be passed and plasmons will not radiate light.

Note that a recent debate over the source of "extraordinary enhancement" has generated some hostilities (see American Scientist Jan/Feb 2006), is it plasmons or diffraction effects of light-evanescent waves? This debate centers around subwavelength apertures, however, not the Kretschmann-Raether configuration. (Search the Web for dozens of free pdf's from academia, a hot topic in nano circles.)