2. Physical principle of surface plasmon wave generation

2.1 Requirements for surface plasmon wave generation

The most commonly used approach to surface plasmon wave excitation involves exploiting the total internal reflection of light at the interface between a flat face of a prism coated with a nanometric layer of a noble metal (usually gold or silver) and the external medium. The result is an evanescent wave that propagates through the metal layer. This wave excites the surface plasmon wave when the component of its propagation constant parallel to the metal surface (also called the "tangential component") is equal to that of the plasmon wave. This is equivalent to verifying the following relationship