Introduction

A wide variety of optical techniques have been developed for exciting SPs. As seen in Chapters 8 and 9, it is possible to excite localized SPs on nanowires and nanoparticles simply by shining a beam of light on these surfaces. On the other hand, it is not as simple to excite the nonradiative SPs on planar surfaces that do not directly couple to an incident plane wave, because the momentum of the incident photon cannot be matched to that of the SP. As described in Section 2.16, there are several approaches for overcoming this difficulty, including focusing a beam of light on the edge of a metallic film (end-fire coupling), using a diffraction grating to directly match the wave vector of the incident photon to that of the SP, or using attenuated total reflection via prism coupling. The prism-coupling equations were derived in Chapter 2 and the important aspects of resonance angle and line width were discussed and illustrated in detail. In this chapter we do not rederive those results, but rather, discuss some of the practical issues involved in using these configurations, and especially make use of those results for comparison to the grating coupler. The mathematics of vector diffraction, which is necessary for studying the grating coupler, is described in detail in the appendix of this chapter, which can be found online in the supplementary material at www.cambridge.org/9780521767170.