ABSTRACT
Surface plasmon resonance (SPR) is an extremely useful optical method for studying label-free biomolecular interaction in real time within a variety of diversified areas like biomedicine, life sciences, electrochemistry, food and environmental safety, and many more. The simplest technique used for detection employs the Kretschmann configuration, which is when light passing through a prism is allowed to fall on a metal sensor surface and it reflects off from the back side of the sensor surface. At a particular angle, known as the resonance angle, absorption of light by the electrons present in the metal film causes them to resonate; these resonating electrons are known as surface plasmons. Interaction of photons of incident polarized light with the free electrons of the metal layer takes place through the evanescent waves. The phenomenon and working of SPRs are discussed in this chapter in detail along with the excitation condition and dispersion relation for SPR. Three important optical configurations of SPR, namely Grating, Otto, and Kretschmann configurations, by which excitation of plasmons is achieved, are discussed. The mechanism of enhancement in terahertz (THz) output by surface plasmon excitation is finally examined.
