HYDRODYNAMIC STUDY OF SURFACE-PLASMON ENHANCED NONLOCAL 2ND-HARMONIC GENERATION

A theoretical calculation of optical second-harmonic generation from a free-electron-like metal surface is presented. The metal is assumed t o be semi-infinite with a flat surface. An excitation by a plane monoc hromatic electromagnetic wave incident upon the surface is considered in two geometries: (i) free surface and (ii) prism coupler in Otto con figuration. The analytical expression of the second-harmonic reflectiv ity in the full hydrodynamic approach is derived. The important point is that the formalism we use leads to an analytical expression of this reflectivity. This allows an easy physical insight into the second-ha rmonic process at metal surfaces. The result is compared with previous calculations. It is also demonstrated how easily this calculation can be extended to the prism coupler.